1
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Zeng W, Chen W, Liu Y, Zhang T, Zhai C, Li W, Wang L, Zhang C, Zeng Q, Wang F, Ma L. Preamplification-free ultra-fast and ultra-sensitive point-of-care testing via LwaCas13a. Biosens Bioelectron 2024; 259:116400. [PMID: 38776799 DOI: 10.1016/j.bios.2024.116400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 05/02/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Abstract
CRISPR based nucleic acid detection technology provides a deployable approach to point of care testing. While, there remain challenges limiting its practical applications, such as the need for pre-amplification and the long turnaround time. Here, we present a self-cascade signal amplification method with LwaCas13a and an artificially designed "U" rich RNA of stem-loop structure (URH) for pre-amplification-free ultra-fast and ultra-sensitive point-of-care testing (PASSPORT). The PASSPORT system contains: URH, crRNA targeted the URH, crRNA targeted the interesting RNA, fluorescent RNA reporter and LwaCas13a. The assay realized the detection of 100 copies/mL, within 5 min. The PASSPORT platform was further adopted for the detection of marker gene from SASR-CoV-2 and Severe fever with thrombocytopenia syndrome virus (SFTSV), respectively, and 100% accuracy for the analysis of clinical specimens (100 SASR-CoV-2 specimens and 16 SFTSV specimens) was obtained. Integrated with a lateral flow assay device, this assay could provide an alternative platform for the development of point of care testing (POCT) biosensors. PASSPORT has the potential to enable sensitive, specific, user-friendly, rapid, affordable, equipment-free and point-of-care testing for the purpose of large-scale screening and in case of epidemic outbreak.
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Affiliation(s)
- Wanting Zeng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Wanping Chen
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Yang Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Ting Zhang
- Hubei Provincial Center for Disease Control and Prevention, Wuhan, 430079, China
| | - Chao Zhai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Wenqiang Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Longyu Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Cheng Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China
| | - Qili Zeng
- Hubei Provincial Center for Disease Control and Prevention, Wuhan, 430079, China
| | - Fei Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China.
| | - Lixin Ma
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Province Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, China.
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2
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Wang X, Xu N, Zhu L, Yang H, Li C, Tian H, Xu W. Structural Antagonism-Aided Conformational Regulation Enables an Aptamer-Loop G-Quadruplex Modular Sensor of β-Lactoglobulin. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307995. [PMID: 38212277 DOI: 10.1002/smll.202307995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/13/2023] [Indexed: 01/13/2024]
Abstract
A simple, reliable method for identifying β-lactoglobulin (β-LG) in dairy products is needed to protect those with β-LG allergies. A common, practical strategy for target detection is designing simplified nucleic acid nanodevices by integrating functional components. This work presents a label-free modular β-LG aptasensor consisting of an aptamer-loop G-quadruplex (G4), the working conformation of which is regulated by conformational antagonism to ensure respective module functionality and the related signal transduction. The polymorphic conformations of the module-fused sequence are systematically characterized, and the cause is revealed as shifting antagonistic equilibrium. Combined with conformational folding dynamics, this helped regulate functional conformations by fine-tuning the sequences. Furthermore, the principle of specific β-LG detection by parallel G4 topology is examined as binding on the G4 aptamer loop by β-LG to reinforce the G4 topology and fluorescence. Finally, a label-free, assembly-free, succinct, and turn-on fluorescent aptasensor is established, achieving excellent sensitivity across five orders of magnitude, rapidly detecting β-LG within 22-min. This study provides a generalizable approach for the conformational regulation of module-fused G4 sequences and a reference model for creating simplified sensing devices for a variety of targets.
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Affiliation(s)
- Xinxin Wang
- College of Food Science and Technology, Hebei Agricultural University, Baoding, 071001, China
- College of Life Science and Engineering, Handan University, Handan, 056005, China
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Ning Xu
- School of Life Science, Tsinghua University, Beijing, 100091, China
| | - Longjiao Zhu
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - He Yang
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
| | - Chen Li
- College of Food Science and Technology, Hebei Agricultural University, Baoding, 071001, China
| | - Hongtao Tian
- College of Food Science and Technology, Hebei Agricultural University, Baoding, 071001, China
| | - Wentao Xu
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing, 100191, China
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3
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Sanchez A, Ortega P, Sakhtemani R, Manjunath L, Oh S, Bournique E, Becker A, Kim K, Durfee C, Temiz NA, Chen XS, Harris RS, Lawrence MS, Buisson R. Mesoscale DNA features impact APOBEC3A and APOBEC3B deaminase activity and shape tumor mutational landscapes. Nat Commun 2024; 15:2370. [PMID: 38499542 PMCID: PMC10948877 DOI: 10.1038/s41467-024-45909-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/09/2024] [Indexed: 03/20/2024] Open
Abstract
Antiviral DNA cytosine deaminases APOBEC3A and APOBEC3B are major sources of mutations in cancer by catalyzing cytosine-to-uracil deamination. APOBEC3A preferentially targets single-stranded DNAs, with a noted affinity for DNA regions that adopt stem-loop secondary structures. However, the detailed substrate preferences of APOBEC3A and APOBEC3B have not been fully established, and the specific influence of the DNA sequence on APOBEC3A and APOBEC3B deaminase activity remains to be investigated. Here, we find that APOBEC3B also selectively targets DNA stem-loop structures, and they are distinct from those subjected to deamination by APOBEC3A. We develop Oligo-seq, an in vitro sequencing-based method to identify specific sequence contexts promoting APOBEC3A and APOBEC3B activity. Through this approach, we demonstrate that APOBEC3A and APOBEC3B deaminase activity is strongly regulated by specific sequences surrounding the targeted cytosine. Moreover, we identify the structural features of APOBEC3B and APOBEC3A responsible for their substrate preferences. Importantly, we determine that APOBEC3B-induced mutations in hairpin-forming sequences within tumor genomes differ from the DNA stem-loop sequences mutated by APOBEC3A. Together, our study provides evidence that APOBEC3A and APOBEC3B can generate distinct mutation landscapes in cancer genomes, driven by their unique substrate selectivity.
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Affiliation(s)
- Ambrocio Sanchez
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Pedro Ortega
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Ramin Sakhtemani
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Lavanya Manjunath
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Sunwoo Oh
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Elodie Bournique
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Alexandrea Becker
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Kyumin Kim
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Cameron Durfee
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Nuri Alpay Temiz
- Institute for Health Informatics, University of Minnesota, Minneapolis, MN, USA
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Reuben S Harris
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX, USA
- Howard Hughes Medical Institute, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Rémi Buisson
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA.
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA.
- Department of Pharmaceutical Sciences, School of Pharmacy & Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA.
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4
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Luo Y, Živković ML, Wang J, Ryneš J, Foldynová-Trantírková S, Trantírek L, Verga D, Mergny JL. A sodium/potassium switch for G4-prone G/C-rich sequences. Nucleic Acids Res 2024; 52:448-461. [PMID: 37986223 PMCID: PMC10783510 DOI: 10.1093/nar/gkad1073] [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: 06/10/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/22/2023] Open
Abstract
Metal ions are essential components for the survival of living organisms. For most species, intracellular and extracellular ionic conditions differ significantly. As G-quadruplexes (G4s) are ion-dependent structures, changes in the [Na+]/[K+] ratio may affect the folding of genomic G4s. More than 11000 putative G4 sequences in the human genome (hg19) contain at least two runs of three continuous cytosines, and these mixed G/C-rich sequences may form a quadruplex or a competing hairpin structure based on G-C base pairing. In this study, we examine how the [Na+]/[K+] ratio influences the structures of G/C-rich sequences. The natural G4 structure with a 9-nt long central loop, CEBwt, was chosen as a model sequence, and the loop bases were gradually replaced by cytosines. The series of CEB mutations revealed that the presence of cytosines in G4 loops does not prevent G4 folding or decrease G4 stability but increases the probability of forming a competing structure, either a hairpin or an intermolecular duplex. Slow conversion to the quadruplex in vitro (in a potassium-rich buffer) and cells was demonstrated by NMR. 'Shape-shifting' sequences may respond to [Na+]/[K+] changes with delayed kinetics.
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Affiliation(s)
- Yu Luo
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
| | - Martina Lenarčič Živković
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
- Slovenian NMR Centre, National Institute of Chemistry, SI-1000 Ljubljana, Slovenia
| | - Jiawei Wang
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Jan Ryneš
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | | | - Lukáš Trantírek
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Daniela Verga
- CNRS UMR9187, INSERM U1196, Université Paris-Saclay, F-91405 Orsay, France
- CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, F-91405 Orsay, France
| | - Jean-Louis Mergny
- Laboratoire d’Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, 91128 Palaiseau, France
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5
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Wang G. Thermoring basis for the TRPV3 bio-thermometer. Sci Rep 2023; 13:21594. [PMID: 38062125 PMCID: PMC10703924 DOI: 10.1038/s41598-023-47100-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 11/09/2023] [Indexed: 12/18/2023] Open
Abstract
The thermosensitive transient receptor potential (TRP) channels are well-known as bio-thermometers with specific temperature thresholds and sensitivity. However, their precise structural origins are still mysterious. Here, graph theory was used to test how the temperature-dependent non-covalent interactions as identified in the 3D structures of thermo-gated TRPV3 could form a systematic fluidic grid-like mesh network with the constrained thermo-rings from the biggest grids to the smallest ones as necessary structural motifs for the variable temperature thresholds and sensitivity. The results showed that the heat-evoked melting of the biggest grids may control the specific temperature thresholds to initiate channel gating while the smaller grids may be required to secure heat efficacy. Together, all the grids along the lipid-dependent minimal gating pathway may be necessary to change with molar heat capacity for the specific temperature sensitivity. Therefore, this graph theory-based grid thermodynamic model may provide an extensive structural basis for the thermo-gated TRP channels.
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Affiliation(s)
- Guangyu Wang
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA, 95616, USA.
- Department of Drug Research and Development, Institute of Biophysical Medico-Chemistry, Reno, NV, 89523, USA.
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6
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Solomun T, Cordsmeier L, Hallier DC, Seitz H, Hahn MB. Interaction of a Dimeric Single-Stranded DNA-Binding Protein (G5P) with DNA Hairpins. A Molecular Beacon Study. J Phys Chem B 2023; 127:8131-8138. [PMID: 37704207 PMCID: PMC10544328 DOI: 10.1021/acs.jpcb.3c03669] [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: 05/31/2023] [Revised: 08/23/2023] [Indexed: 09/15/2023]
Abstract
Gene-V protein (G5P/GVP) is a single-stranded (ss)DNA-binding protein (SBP) of bacteriophage f1 that is required for DNA synthesis and repair. In solution, it exists as a dimer that binds two antiparallel ssDNA strands with high affinity in a cooperative manner, forming a left-handed helical protein-DNA filament. Here, we report on fluorescence studies of the interaction of G5P with different DNA oligonucleotides having a hairpin structure (molecular beacon, MB) with a seven base-pair stem (dT24-stem7, dT18-stem7), as well as with DNA oligonucleotides (dT38, dT24) without a defined secondary structure. All oligonucleotides were end-labeled with a Cy3-fluorophore and a BHQ2-quencher. In the case of DNA oligonucleotides without a secondary structure, an almost complete quenching of their strong fluorescence (with about 5% residual intensity) was observed upon the binding of G5P. This implies an exact alignment of the ends of the DNA strand(s) in the saturated complex. The interaction of the DNA hairpins with G5P led to the unzipping of the base-paired stem, as revealed by fluorescence measurements, fluorescence microfluidic mixing experiments, and electrophoretic mobility shift assay data. Importantly, the disruption of ssDNA's secondary structure agrees with the behavior of other single-stranded DNA-binding proteins (SBPs). In addition, substantial protein-induced fluorescence enhancement (PIFE) of the Cy3-fluorescence was observed.
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Affiliation(s)
- Tihomir Solomun
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
| | - Leo Cordsmeier
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
- Institut
für Chemie, Freie Universität
Berlin, Berlin 14195, Germany
| | - Dorothea C. Hallier
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
- Institut
für Biochemie und Biologie, Universität
Potsdam, Potsdam 14476, Germany
- Fraunhofer
Institut für Zelltherapie und Immunologie Institutsteil Bioanalytik
und Bioprozesse IZI-BB, Potsdam 14476, Germany
| | - Harald Seitz
- Institut
für Biochemie und Biologie, Universität
Potsdam, Potsdam 14476, Germany
- Fraunhofer
Institut für Zelltherapie und Immunologie Institutsteil Bioanalytik
und Bioprozesse IZI-BB, Potsdam 14476, Germany
| | - Marc Benjamin Hahn
- Bundesanstalt
für Materialforschung und -prüfung (BAM), Berlin 12205, Germany
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7
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Sanchez A, Ortega P, Sakhtemani R, Manjunath L, Oh S, Bournique E, Becker A, Kim K, Durfee C, Temiz NA, Chen XS, Harris RS, Lawrence MS, Buisson R. Mesoscale DNA Features Impact APOBEC3A and APOBEC3B Deaminase Activity and Shape Tumor Mutational Landscapes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.02.551499. [PMID: 37577509 PMCID: PMC10418229 DOI: 10.1101/2023.08.02.551499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Antiviral DNA cytosine deaminases APOBEC3A and APOBEC3B are major sources of mutations in cancer by catalyzing cytosine-to-uracil deamination. APOBEC3A preferentially targets singlestranded DNAs, with a noted affinity for DNA regions that adopt stem-loop secondary structures. However, the detailed substrate preferences of APOBEC3A and APOBEC3B have been fully established, and the specific influence of the DNA sequence on APOBEC3A APOBEC3B deaminase activity remains to be investigated. Here, we find that APOBEC3B selectively targets DNA stem-loop structures, and they are distinct from those subjected deamination by APOBEC3A. We develop Oligo-seq, a novel in vitro sequencing-based to identify specific sequence contexts promoting APOBEC3A and APOBEC3B activity. Through this approach, we demonstrate that APOBEC3A an APOBEC3B deaminase activity is strongly regulated by specific sequences surrounding the targeted cytosine. Moreover, we identify structural features of APOBEC3B and APOBEC3A responsible for their substrate preferences. Importantly, we determine that APOBEC3B-induced mutations in hairpin-forming sequences within tumor genomes differ from the DNA stem-loop sequences mutated by APOBEC3A. Together, our study provides evidence that APOBEC3A and APOBEC3B can generate mutation landscapes in cancer genomes, driven by their unique substrate selectivity.
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8
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Wang G. Thermoring basis for the TRPV3 bio-thermometer. RESEARCH SQUARE 2023:rs.3.rs-2987105. [PMID: 37398446 PMCID: PMC10312932 DOI: 10.21203/rs.3.rs-2987105/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The thermosensitive transient receptor potential (TRP) channels are well-known as bio-thermometers with specific temperature thresholds and sensitivity. However, their structural origins are still mysterious. Here, graph theory was used to test how the temperature-dependent non-covalent interactions as identified in the 3D structures of thermo-gated TRPV3 could form a systematic fluidic grid-like mesh network with the thermal rings from the biggest grids to the smallest ones as necessary structural motifs for the variable temperature thresholds and sensitivity. The results showed that the heat-evoked melting of the biggest grids may control temperature thresholds to activate the channel while the smaller grids may act as thermo-stable anchors to secure the channel activity. Together, all the grids along the gating pathway may be necessary for the specific temperature sensitivity. Therefore, this grid thermodynamic model may provide an extensive structural basis for the thermo-gated TRP channels.
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9
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Rudra S, Chauhan K, Singh AR, Kumar S. Force-induced melting of DNA hairpin: Unfolding pathways and phase diagrams. Phys Rev E 2023; 107:054501. [PMID: 37328992 DOI: 10.1103/physreve.107.054501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/27/2023] [Indexed: 06/18/2023]
Abstract
Using the exact enumeration technique, we have studied the force-induced melting of a DNA hairpin on the face centered cubic lattice for two different sequences which differ in terms of loop closing base pairs. The melting profiles obtained from the exact enumeration technique is consistent with the Gaussian network model and Langevin dynamics simulations. Probability distribution analysis based on the exact density of states revealed the microscopic details of the opening of the hairpin. We showed the existence of intermediate states near the melting temperature. We further showed that different ensembles used to model single-molecule force spectroscopy setups may give different force-temperature diagrams. We delineate the possible reasons for the observed discrepancies.
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Affiliation(s)
- Sumitra Rudra
- Department of Physics, Banaras Hindu University, Varanasi 221005, India
| | - Keerti Chauhan
- Department of Physics, Banaras Hindu University, Varanasi 221005, India
| | - Amit Raj Singh
- Department of Physics, Graphic Era Hill University, Dehradun 248002, India
| | - Sanjay Kumar
- Department of Physics, Banaras Hindu University, Varanasi 221005, India
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10
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Pundir M, De Rosa MC, Lobanova L, Abdulmawjood S, Chen X, Papagerakis S, Papagerakis P. Structural properties and binding mechanism of DNA aptamers sensing saliva melatonin for diagnosis and monitoring of circadian clock and sleep disorders. Anal Chim Acta 2023; 1251:340971. [PMID: 36925277 DOI: 10.1016/j.aca.2023.340971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/25/2023] [Accepted: 02/12/2023] [Indexed: 02/17/2023]
Abstract
Circadian desynchrony with the external light-dark cycle influences the rhythmic secretion of melatonin which is among the first signs of circadian rhythm sleep disorders. An accurate dim light melatonin onset (established indicator of circadian rhythm sleep disorders) measurement requires lengthy assays, and antibody affinities alterations, especially in patients with circadian rhythm disorders whose melatonin salivary levels vary significantly, making antibodies detection mostly inadequate. In contrast, aptamers with their numerous advantages (e.g., target selectivity, structural flexibility in tuning binding affinities, small size, etc.) can become preferable biorecognition molecules for salivary melatonin detection with high sensitivity and specificity. This study thoroughly characterizes the structural property and binding mechanism of a single-stranded DNA aptamer full sequence (MLT-C-1) and its truncated versions (MLT-A-2, MLT-A-4) to decipher its optimal characteristics for saliva melatonin detection. We use circular dichroism spectroscopy to determine aptamers' conformational changes under different ionic strengths and showed that aptamers display a hairpin loop structure where few base pairs in the stem play a significant role in melatonin binding and formation of aptamer stabilized structure. Through microscale thermophoresis, aptamers demonstrated a high binding affinity in saliva samples (MLT-C-1F Kd = 12.5 ± 1.7 nM; MLT-A-4F Kd = 11.2 ± 1.6 nM; MLT-A-2F Kd = 2.4 ± 2.8 nM; limit-of-detection achieved in pM, highest sensitivity attained for MLT-A-2F aptamer with the lowest detection limit of 1.35 pM). Our data suggest that aptamers are promising as biorecognition molecules and provide the baseline parameters for the development of an aptamer-based point-of-care diagnostic system for melatonin detection and accurate profiling of its fluctuations in saliva.
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Affiliation(s)
- Meenakshi Pundir
- Laboratory of Precision Oral Health and Chronobiology, College of Dentistry, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada; Division of Biomedical Engineering, University of Saskatchewan, 57 Campus Dr, Saskatoon, S7K 5A9, Canada; Laboratory of Oral, Head and Neck Cancer - Personalized Diagnostics and Therapeutics, Department of Surgery, College of Medicine, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada
| | - Maria C De Rosa
- Department of Chemistry, Faculty of Science, Carleton University, 1125 Colonel by Drive, Ottawa, Ontario, K1S 5B6, Canada.
| | - Liubov Lobanova
- Laboratory of Precision Oral Health and Chronobiology, College of Dentistry, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada
| | - Shahad Abdulmawjood
- Department of Chemistry, Faculty of Science, Carleton University, 1125 Colonel by Drive, Ottawa, Ontario, K1S 5B6, Canada
| | - Xiongbiao Chen
- Division of Biomedical Engineering, University of Saskatchewan, 57 Campus Dr, Saskatoon, S7K 5A9, Canada; Department of Mechanical Engineering, School of Engineering, University of Saskatchewan, 57 Campus Dr, S7K 5A9, Saskatoon, Canada.
| | - Silvana Papagerakis
- Laboratory of Precision Oral Health and Chronobiology, College of Dentistry, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada; Laboratory of Oral, Head and Neck Cancer - Personalized Diagnostics and Therapeutics, Department of Surgery, College of Medicine, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada; Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Michigan, 1500 E Medical Center Dr, Ann Arbor, MI, 48109, United States.
| | - Petros Papagerakis
- Laboratory of Precision Oral Health and Chronobiology, College of Dentistry, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, S7N 5E4, Canada; Division of Biomedical Engineering, University of Saskatchewan, 57 Campus Dr, Saskatoon, S7K 5A9, Canada.
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11
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Jang SS, Dubnik S, Hon J, Hellenkamp B, Lynall DG, Shepard KL, Nuckolls C, Gonzalez RL. Characterizing the Conformational Free-Energy Landscape of RNA Stem-Loops Using Single-Molecule Field-Effect Transistors. J Am Chem Soc 2023; 145:402-412. [PMID: 36547391 PMCID: PMC10025942 DOI: 10.1021/jacs.2c10218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We have developed and used single-molecule field-effect transistors (smFETs) to characterize the conformational free-energy landscape of RNA stem-loops. Stem-loops are one of the most common RNA structural motifs and serve as building blocks for the formation of complex RNA structures. Given their prevalence and integral role in RNA folding, the kinetics of stem-loop (un)folding has been extensively characterized using both experimental and computational approaches. Interestingly, these studies have reported vastly disparate timescales of (un)folding, which has been interpreted as evidence that (un)folding of even simple stem-loops occurs on a highly rugged conformational energy landscape. Because smFETs do not rely on fluorophore reporters of conformation or mechanical (un)folding forces, they provide a unique approach that has allowed us to directly monitor tens of thousands of (un)folding events of individual stem-loops at a 200 μs time resolution. Our results show that under our experimental conditions, stem-loops (un)fold over a 1-200 ms timescale during which they transition between ensembles of unfolded and folded conformations, the latter of which is composed of at least two sub-populations. The 1-200 ms timescale of (un)folding we observe here indicates that smFETs report on complete (un)folding trajectories in which unfolded conformations of the RNA spend long periods of time wandering the free-energy landscape before sampling one of several misfolded conformations or the natively folded conformation. Our findings highlight the extremely rugged landscape on which even the simplest RNA structural elements fold and demonstrate that smFETs are a unique and powerful approach for characterizing the conformational free-energy of RNA.
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Affiliation(s)
- Sukjin S. Jang
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
| | - Sarah Dubnik
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
| | - Jason Hon
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
| | - Björn Hellenkamp
- Department of Electrical Engineering, Columbia University, 3000 Broadway, New York, 10027, USA
| | - David G. Lynall
- Department of Electrical Engineering, Columbia University, 3000 Broadway, New York, 10027, USA
| | - Kenneth L. Shepard
- Department of Electrical Engineering, Columbia University, 3000 Broadway, New York, 10027, USA
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
| | - Ruben L. Gonzalez
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA
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12
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Mu ZC, Tan YL, Zhang BG, Liu J, Shi YZ. Ab initio predictions for 3D structure and stability of single- and double-stranded DNAs in ion solutions. PLoS Comput Biol 2022; 18:e1010501. [PMID: 36260618 PMCID: PMC9621594 DOI: 10.1371/journal.pcbi.1010501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/31/2022] [Accepted: 09/27/2022] [Indexed: 11/07/2022] Open
Abstract
The three-dimensional (3D) structure and stability of DNA are essential to understand/control their biological functions and aid the development of novel materials. In this work, we present a coarse-grained (CG) model for DNA based on the RNA CG model proposed by us, to predict 3D structures and stability for both dsDNA and ssDNA from the sequence. Combined with a Monte Carlo simulated annealing algorithm and CG force fields involving the sequence-dependent base-pairing/stacking interactions and an implicit electrostatic potential, the present model successfully folds 20 dsDNAs (≤52nt) and 20 ssDNAs (≤74nt) into the corresponding native-like structures just from their sequences, with an overall mean RMSD of 3.4Å from the experimental structures. For DNAs with various lengths and sequences, the present model can make reliable predictions on stability, e.g., for 27 dsDNAs with/without bulge/internal loops and 24 ssDNAs including pseudoknot, the mean deviation of predicted melting temperatures from the corresponding experimental data is only ~2.0°C. Furthermore, the model also quantificationally predicts the effects of monovalent or divalent ions on the structure stability of ssDNAs/dsDNAs. To determine 3D structures and quantify stability of single- (ss) and double-stranded (ds) DNAs is essential to unveil the mechanisms of their functions and to further guide the production and development of novel materials. Although many DNA models have been proposed to reproduce the basic structural, mechanical, or thermodynamic properties of dsDNAs based on the secondary structure information or preset constraints, there are very few models can be used to investigate the ssDNA folding or dsDNA assembly from the sequence. Furthermore, due to the polyanionic nature of DNAs, metal ions (e.g., Na+ and Mg2+) in solutions can play an essential role in DNA folding and dynamics. Nevertheless, ab initio predictions for DNA folding in ion solutions are still an unresolved problem. In this work, we developed a novel coarse-grained model to predict 3D structures and thermodynamic stabilities for both ssDNAs and dsDNAs in monovalent/divalent ion solutions from their sequences. As compared with the extensive experimental data and available existing models, we showed that the present model can successfully fold simple DNAs into their native-like structures, and can also accurately reproduce the effects of sequence and monovalent/divalent ions on structure stability for ssDNAs including pseudoknot and dsDNAs with/without bulge/internal loops.
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Affiliation(s)
- Zi-Chun Mu
- Research Center of Nonlinear Science, School of Mathematical & Physical Sciences, Wuhan Textile University, Wuhan, China
- School of Computer Science and Artificial Intelligence, Wuhan Textile University, Wuhan, China
| | - Ya-Lan Tan
- Research Center of Nonlinear Science, School of Mathematical & Physical Sciences, Wuhan Textile University, Wuhan, China
| | - Ben-Gong Zhang
- Research Center of Nonlinear Science, School of Mathematical & Physical Sciences, Wuhan Textile University, Wuhan, China
| | - Jie Liu
- Research Center of Nonlinear Science, School of Mathematical & Physical Sciences, Wuhan Textile University, Wuhan, China
| | - Ya-Zhou Shi
- Research Center of Nonlinear Science, School of Mathematical & Physical Sciences, Wuhan Textile University, Wuhan, China
- * E-mail:
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13
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Zand Karimi H, Innes RW. Molecular mechanisms underlying host-induced gene silencing. THE PLANT CELL 2022; 34:3183-3199. [PMID: 35666177 PMCID: PMC9421479 DOI: 10.1093/plcell/koac165] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/08/2022] [Indexed: 05/05/2023]
Abstract
Host-induced gene silencing (HIGS) refers to the silencing of genes in pathogens and pests by expressing homologous double-stranded RNAs (dsRNA) or artificial microRNAs (amiRNAs) in the host plant. The discovery of such trans-kingdom RNA silencing has enabled the development of RNA interference-based approaches for controlling diverse crop pathogens and pests. Although HIGS is a promising strategy, the mechanisms by which these regulatory RNAs translocate from plants to pathogens, and how they induce gene silencing in pathogens, are poorly understood. This lack of understanding has led to large variability in the efficacy of various HIGS treatments. This variability is likely due to multiple factors, such as the ability of the target pathogen or pest to take up and/or process RNA from the host, the specific genes and target sequences selected in the pathogen or pest for silencing, and where, when, and how the dsRNAs or amiRNAs are produced and translocated. In this review, we summarize what is currently known about the molecular mechanisms underlying HIGS, identify key unanswered questions, and explore strategies for improving the efficacy and reproducibility of HIGS treatments in the control of crop diseases.
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Affiliation(s)
- Hana Zand Karimi
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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14
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Tang K, Roca J, Chen R, Ansari A, Liang J. Thermodynamics of unfolding mechanisms of mouse mammary tumor virus pseudoknot from a coarse-grained loop-entropy model. J Biol Phys 2022; 48:129-150. [PMID: 35445347 DOI: 10.1007/s10867-022-09602-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Pseudoknotted RNA molecules play important biological roles that depend on their folded structure. To understand the underlying principles that determine their thermodynamics and folding/unfolding mechanisms, we carried out a study on a variant of the mouse mammary tumor virus pseudoknotted RNA (VPK), a widely studied model system for RNA pseudoknots. Our method is based on a coarse-grained discrete-state model and the algorithm of PK3D (pseudoknot structure predictor in three-dimensional space), with RNA loops explicitly constructed and their conformational entropic effects incorporated. Our loop entropy calculations are validated by accurately capturing previously measured melting temperatures of RNA hairpins with varying loop lengths. For each of the hairpins that constitutes the VPK, we identified alternative conformations that are more stable than the hairpin structures at low temperatures and predicted their populations at different temperatures. Our predictions were validated by thermodynamic experiments on these hairpins. We further computed the heat capacity profiles of VPK, which are in excellent agreement with available experimental data. Notably, our model provides detailed information on the unfolding mechanisms of pseudoknotted RNA. Analysis of the distribution of base-pairing probability of VPK reveals a cooperative unfolding mechanism instead of a simple sequential unfolding of first one stem and then the other. Specifically, we find a simultaneous "loosening" of both stems as the temperature is raised, whereby both stems become partially melted and co-exist during the unfolding process.
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Affiliation(s)
- Ke Tang
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 851 S Morgan St, Chicago, 60607, IL, USA
| | - Jorjethe Roca
- Department of Physics, University of Illinois at Chicago, 845 W Taylor St, Chicago, 60607, IL, USA
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, 21218, MD, USA
| | - Rong Chen
- Department of Statistics, Rutgers University, 110 Frelinghuysen Rd, Piscataway, 08854, NJ, USA
| | - Anjum Ansari
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 851 S Morgan St, Chicago, 60607, IL, USA.
- Department of Physics, University of Illinois at Chicago, 845 W Taylor St, Chicago, 60607, IL, USA.
| | - Jie Liang
- Richard and Loan Hill Department of Biomedical Engineering, University of Illinois at Chicago, 851 S Morgan St, Chicago, 60607, IL, USA.
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15
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Shokri E, Hosseini M, Boldaji MN, Shahsavar K, amiri-Sadeghan A, Nasiri N, Bahmani A, Ganjali MR, Saboury AA. A novel DNA/hemin complex with enzyme-like activity selected from a hairpin DNAs library at zero H2O2 concentration. MOLECULAR CATALYSIS 2022. [DOI: 10.1016/j.mcat.2022.112156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Tian S, Welte T, Mai J, Liu Y, Ramirez M, Shen H. Identification of an Aptamer With Binding Specificity to Tumor-Homing Myeloid-Derived Suppressor Cells. Front Pharmacol 2022; 12:752934. [PMID: 35126104 PMCID: PMC8814529 DOI: 10.3389/fphar.2021.752934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 12/31/2021] [Indexed: 11/23/2022] Open
Abstract
Myeloid-derived suppressor cells (MDSCs) play a critical role in tumor growth and metastasis. Since they constantly infiltrate into the tumor tissue, these cells are considered as an ideal carrier for tumor-targeted drug delivery. We recently identified a DNA-based thioaptamer (T1) with tumor accumulating activity, demonstrated its potential on tumor targeting and drug delivery. In the current study, we have carried out structure-activity relationship analysis to further optimize the aptamer. In the process, we have identified a sequence-modified aptamer (M1) that shows an enhanced binding affinity to MDSCs over the parental T1 aptamer. In addition, M1 can penetrate into the tumor tissue more effectively by hitchhiking on MDSCs. Taken together, we have identified a new reagent for enhanced tumor-targeted drug delivery.
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Affiliation(s)
- Shaohui Tian
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States,Department of Gastrointestinal Surgery, The Third Xiangya Hospital of Central South University, Changsha, China
| | - Thomas Welte
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States
| | - Junhua Mai
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States
| | - Yongbin Liu
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States
| | - Maricela Ramirez
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States
| | - Haifa Shen
- Department of Nanomedicine, Houston Methodist Academic Institute, Houston, TX, United States,Weill Cornell Medical College, White Plains, NY, United States,*Correspondence: Haifa Shen,
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17
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Ravichandran S, Razzaq M, Parveen N, Ghosh A, Kim KK. The effect of hairpin loop on the structure and gene expression activity of the long-loop G-quadruplex. Nucleic Acids Res 2021; 49:10689-10706. [PMID: 34450640 PMCID: PMC8501965 DOI: 10.1093/nar/gkab739] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/10/2021] [Accepted: 08/24/2021] [Indexed: 12/29/2022] Open
Abstract
G-quadruplex (G4), a four-stranded DNA or RNA structure containing stacks of guanine tetrads, plays regulatory roles in many cellular functions. So far, conventional G4s containing loops of 1–7 nucleotides have been widely studied. Increasing experimental evidence suggests that unconventional G4s, such as G4s containing long loops (long-loop G4s), play a regulatory role in the genome by forming a stable structure. Other secondary structures such as hairpins in the loop might thus contribute to the stability of long-loop G4s. Therefore, investigation of the effect of the hairpin-loops on the structure and function of G4s is required. In this study, we performed a systematic biochemical investigation of model G4s containing long loops with various sizes and structures. We found that the long-loop G4s are less stable than conventional G4s, but their stability increased when the loop forms a hairpin (hairpin-G4). We also verified the biological significance of hairpin-G4s by showing that hairpin-G4s present in the genome also form stable G4s and regulate gene expression as confirmed by in cellulo reporter assays. This study contributes to expanding the scope and diversity of G4s, thus facilitating future studies on the role of G4s in the human genome.
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Affiliation(s)
- Subramaniyam Ravichandran
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Maria Razzaq
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Nazia Parveen
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Ambarnil Ghosh
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
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18
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Largy E, König A, Ghosh A, Ghosh D, Benabou S, Rosu F, Gabelica V. Mass Spectrometry of Nucleic Acid Noncovalent Complexes. Chem Rev 2021; 122:7720-7839. [PMID: 34587741 DOI: 10.1021/acs.chemrev.1c00386] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nucleic acids have been among the first targets for antitumor drugs and antibiotics. With the unveiling of new biological roles in regulation of gene expression, specific DNA and RNA structures have become very attractive targets, especially when the corresponding proteins are undruggable. Biophysical assays to assess target structure as well as ligand binding stoichiometry, affinity, specificity, and binding modes are part of the drug development process. Mass spectrometry offers unique advantages as a biophysical method owing to its ability to distinguish each stoichiometry present in a mixture. In addition, advanced mass spectrometry approaches (reactive probing, fragmentation techniques, ion mobility spectrometry, ion spectroscopy) provide more detailed information on the complexes. Here, we review the fundamentals of mass spectrometry and all its particularities when studying noncovalent nucleic acid structures, and then review what has been learned thanks to mass spectrometry on nucleic acid structures, self-assemblies (e.g., duplexes or G-quadruplexes), and their complexes with ligands.
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Affiliation(s)
- Eric Largy
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Alexander König
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Anirban Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Debasmita Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Sanae Benabou
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Frédéric Rosu
- Univ. Bordeaux, CNRS, INSERM, IECB, UMS 3033, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
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19
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Samaan GN, Wyllie MK, Cizmic JM, Needham LM, Nobis D, Ngo K, Andersen S, Magennis SW, Lee SF, Purse BW. Single-molecule fluorescence detection of a tricyclic nucleoside analogue. Chem Sci 2020; 12:2623-2628. [PMID: 34164030 PMCID: PMC8179283 DOI: 10.1039/d0sc03903a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Fluorescent nucleobase surrogates capable of Watson–Crick hydrogen bonding are essential probes of nucleic acid structure and dynamics, but their limited brightness and short absorption and emission wavelengths have rendered them unsuitable for single-molecule detection. Aiming to improve on these properties, we designed a new tricyclic pyrimidine nucleoside analogue with a push–pull conjugated system and synthesized it in seven sequential steps. The resulting C-linked 8-(diethylamino)benzo[b][1,8]naphthyridin-2(1H)-one nucleoside, which we name ABN, exhibits ε442 = 20 000 M−1 cm−1 and Φem,540 = 0.39 in water, increasing to Φem = 0.50–0.53 when base paired with adenine in duplex DNA oligonucleotides. Single-molecule fluorescence measurements of ABN using both one-photon and two-photon excitation demonstrate its excellent photostability and indicate that the nucleoside is present to > 95% in a bright state with count rates of at least 15 kHz per molecule. This new fluorescent nucleobase analogue, which, in duplex DNA, is the brightest and most red-shifted known, is the first to offer robust and accessible single-molecule fluorescence detection capabilities. Fluorescent nucleoside analogue ABN is readily detected at the single-molecule level and retains a quantum yield >50% in duplex DNA oligonucleotides.![]()
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Affiliation(s)
- George N Samaan
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
| | - Mckenzie K Wyllie
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
| | - Julian M Cizmic
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
| | - Lisa-Maria Needham
- University of Cambridge, Chemistry Department Lensfield Road Cambridge CB2 1EW UK
| | - David Nobis
- School of Chemistry, University of Glasgow University Avenue Glasgow G12 8QQ UK
| | - Katrina Ngo
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
| | - Susan Andersen
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
| | - Steven W Magennis
- School of Chemistry, University of Glasgow University Avenue Glasgow G12 8QQ UK
| | - Steven F Lee
- University of Cambridge, Chemistry Department Lensfield Road Cambridge CB2 1EW UK
| | - Byron W Purse
- Department of Chemistry and Biochemistry and the Viral Information Institute, San Diego State University San Diego CA 92182 USA
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20
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Cheng CH, Ishii K, Tahara T. Microsecond Equilibrium Dynamics of Hairpin-Forming Oligonucleotides Quantified by Two-Color Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy. J Phys Chem B 2020; 124:10673-10681. [PMID: 33200606 DOI: 10.1021/acs.jpcb.0c07600] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
RNA and DNA play distinct roles in biological systems. However, the underlying physicochemical difference has been poorly understood, in particular, that in dynamical aspects. In this paper, we report on a comparative study of the formation-dissociation dynamics of a hairpin structure of RNA and DNA with development of two-color two-dimensional fluorescence lifetime correlation spectroscopy (two-color 2D FLCS). In this extension of 2D FLCS, we newly introduce the two-color detection scheme to analyze not only donor fluorescence photons but also acceptor fluorescence photons from a doubly labeled Förster resonance energy transfer (FRET) pair. This new 2D FLCS is utilized to resolve multiple species present in an equilibrated condition with a microsecond time resolution and enhanced sensitivity, and the combined use with the filtered fluorescence correlation spectroscopy (FCS) method enables a quantitative discussion on microsecond structural dynamics occurring in the equilibrium. This integrated approach is applied to FRET-labeled RNA/DNA oligonucleotides having analogous hairpin-forming sequences, and it was revealed that the hairpin dissociation rate of RNA is an order of magnitude slower than that of DNA while their hairpin-forming rates are comparable. This marked difference is attributable to the distinct duplex structure of RNA and DNA. The present study demonstrates that the integrated approach combining two-color 2D FLCS and filtered FCS has a high potential for quantifying microsecond kinetics at the single-molecule level, which allows us to experimentally construct a free energy landscape.
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Affiliation(s)
- Chao-Han Cheng
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Kunihiko Ishii
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
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21
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Peng Y, Wang Y, Wang X. Exploring the Thermodynamics of 7-Amino Actinomycin D-Induced Single-Stranded DNA Hairpin by Spectroscopic Techniques and Computational Simulations. J Phys Chem B 2020; 124:10007-10013. [PMID: 33136398 DOI: 10.1021/acs.jpcb.0c05593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
NMR studies have indicated that the anti-tumor therapeutic agent actinomycin D (ACTD) can induce seemingly single-stranded DNA (ssDNA) oligomer 5'-CCGTT3GTGG-3' to form a hairpin structure with tandem GT mismatches at the stem region next to a loop of three stacked thymine bases. In an effort to uncover the preference of binding sequence and to elucidate the thermodynamics properties of the binding, a combination of spectroscopic techniques and computational simulation studies was performed with d(CCGTTnGTGG) and d(CCGAAnGAGG) (denoted as GTTn and GAAn, respectively; n = 3, 5, and 7) sequences. In the presence of 7-amino actinomycin D (7AACTD), all the six oligomers formed stable hairpin structures. The GTT5-7AACTD/GAA5-7AACTD hairpin structure was more stable than the corresponding GTTn-7AACTD and GAAn-7AACTD (n = 3, 7). No significant ΔG difference was observed between GTTn-7AACTD and GAAn-7AACTD complexes with the same loop length. In agreement with the 7AACTD-induced hairpin stability results, the binding affinity of GTTn and GAAn with 7AACTD increased from n = 3 to n = 5 and then decreased when n is 7. Moreover, GTTn and GAAn with the same loop length showed comparable binding affinities to 7AACTD. Furthermore, molecular dynamics simulations found that van der Waals interactions between GTTn/GAAn and 7AACTD were the primary attractive forces for 7AACTD binding, and the electrostatic interactions between the carbonyl groups of 7AACTD and bases in the hairpin were the major unfavorable forces. These findings furthered our understanding that 7AACTD is sensitive to the loop size and sequence as well as tandem GT/GA mismatches of their deoxyribonucleic acid (DNA) targets. A deep understanding of the thermodynamics and the molecular recognition mechanism of 7AACTD with ssDNAs would further the development of ACTD-like antitumor agents.
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Affiliation(s)
- Yinghua Peng
- Key Laboratory of Special Animal Molecular Biology of Jilin Province, Specialty Research Institute of Chinese Academy of Agricultural Sciences, Changchun, Jilin 130022, China
| | - Yibo Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.,Department of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China
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22
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The assessment of three dimensional modelling design for single strand DNA aptamers for computational chemistry application. Biophys Chem 2020; 267:106492. [PMID: 33035750 DOI: 10.1016/j.bpc.2020.106492] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/17/2020] [Accepted: 09/29/2020] [Indexed: 11/23/2022]
Abstract
Aptamers are oligonucleotides and peptides around 15-100 bases in length and are suitable as detection probes or as therapeutics molecules. There are growing interests in the aptamer screening approach through computational simulation methods. DNA and RNA modelling lacks of validation on their predicted 3D structures due to less number of validation tools, unlike protein structures. We suggest an approach to design the stem-loop/hairpin for the three dimensional structure of DNA aptamers through serial applications of computational prediction methods by comparing the simulated structures with the experimental data deposited in PDB Data bank, followed by MD simulations. The result shows minimal structural differences were observed between the designed and the original NMR aptamers, and the stem-loop conformational structures were also retained during the MD thus suggesting the proposed aptamers designing methods are able to synthesize a high quality molecular structure of hairpin aptamers, comparable to the NMR structures.
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23
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Tuske S, Zheng J, Olson ED, Ruiz FX, Pascal BD, Hoang A, Bauman JD, Das K, DeStefano JJ, Musier-Forsyth K, Griffin PR, Arnold E. Integrative structural biology studies of HIV-1 reverse transcriptase binding to a high-affinity DNA aptamer. Curr Res Struct Biol 2020; 2:116-129. [PMID: 33870216 PMCID: PMC8052095 DOI: 10.1016/j.crstbi.2020.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/03/2020] [Accepted: 06/19/2020] [Indexed: 02/07/2023] Open
Abstract
The high-resolution crystal structure of HIV-1 reverse transcriptase (RT) bound to a 38-mer DNA hairpin aptamer with low pM affinity was previously described. The high-affinity binding aptamer contained 2'-O-methyl modifications and a seven base-pair GC-rich tract and the structure of the RT-aptamer complex revealed specific contacts between RT and the template strand of the aptamer. Similar to all crystal structures of RT bound to nucleic acid template-primers, the aptamer bound RT with a bend in the duplex DNA. To understand the structural basis for the ultra-high-affinity aptamer binding, an integrative structural biology approach was used. Hydrogen-deuterium exchange coupled to liquid chromatography-mass spectrometry (HDX-MS) was used to examine the structural dynamics of RT alone and in the presence of the DNA aptamer. RT was selectively labeled with 15N to unambiguously identify peptides from each subunit. HDX of unliganded RT shows a mostly stable core. The p66 fingers and thumb subdomains, and the RNase H domain are relatively dynamic. HDX indicates that both the aptamer and a scrambled version significantly stabilize regions of RT that are dynamic in the absence of DNA. No substantial differences in RT dynamics are observed between aptamer and scrambled aptamer binding, despite a large difference in binding affinity. Small-angle X-ray scattering and circular dichroism spectroscopy were used to investigate the aptamer conformation in solution and revealed a pre-bent DNA that possesses both A- and B-form helical character. Both the 2'-O-methyl modifications and the GC tract appear to contribute to an energetically favorable conformation for binding to RT that contributes to the aptamer's ultra-high affinity for RT. The X-ray structure of RT with an RNA/DNA version of the aptamer at 2.8 Å resolution revealed a potential role of the hairpin positioning in affinity. Together, the data suggest that both the 2'-O-methyl modifications and the GC tract contribute to an energetically favorable conformation for high-affinity binding to RT.
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Affiliation(s)
- Steve Tuske
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
| | - Jie Zheng
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Erik D. Olson
- Department of Chemistry and Biochemistry, Center for RNA Biology, And Center for Retrovirus Research, The Ohio State University, Columbus, OH, 43210, USA
| | - Francesc X. Ruiz
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
| | - Bruce D. Pascal
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Anthony Hoang
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
| | - Joseph D. Bauman
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
| | - Kalyan Das
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
| | - Jeffrey J. DeStefano
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, MD, 20740, USA
| | - Karin Musier-Forsyth
- Department of Chemistry and Biochemistry, Center for RNA Biology, And Center for Retrovirus Research, The Ohio State University, Columbus, OH, 43210, USA
| | - Patrick R. Griffin
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Eddy Arnold
- Center for Advanced Biotechnology and Medicine, And Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, 08854, USA
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Badelt S, Grun C, Sarma KV, Wolfe B, Shin SW, Winfree E. A domain-level DNA strand displacement reaction enumerator allowing arbitrary non-pseudoknotted secondary structures. J R Soc Interface 2020; 17:20190866. [PMID: 32486951 PMCID: PMC7328391 DOI: 10.1098/rsif.2019.0866] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/21/2020] [Indexed: 12/30/2022] Open
Abstract
Information technologies enable programmers and engineers to design and synthesize systems of startling complexity that nonetheless behave as intended. This mastery of complexity is made possible by a hierarchy of formal abstractions that span from high-level programming languages down to low-level implementation specifications, with rigorous connections between the levels. DNA nanotechnology presents us with a new molecular information technology whose potential has not yet been fully unlocked in this way. Developing an effective hierarchy of abstractions may be critical for increasing the complexity of programmable DNA systems. Here, we build on prior practice to provide a new formalization of 'domain-level' representations of DNA strand displacement systems that has a natural connection to nucleic acid biophysics while still being suitable for formal analysis. Enumeration of unimolecular and bimolecular reactions provides a semantics for programmable molecular interactions, with kinetics given by an approximate biophysical model. Reaction condensation provides a tractable simplification of the detailed reactions that respects overall kinetic properties. The applicability and accuracy of the model is evaluated across a wide range of engineered DNA strand displacement systems. Thus, our work can serve as an interface between lower-level DNA models that operate at the nucleotide sequence level, and high-level chemical reaction network models that operate at the level of interactions between abstract species.
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Affiliation(s)
- Stefan Badelt
- California Institute of Technology, Pasadena, CA, USA
| | - Casey Grun
- Wyss Institute, Harvard University, Boston, MA, USA
| | | | - Brian Wolfe
- California Institute of Technology, Pasadena, CA, USA
| | | | - Erik Winfree
- California Institute of Technology, Pasadena, CA, USA
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25
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Ageeli AA, McGovern-Gooch KR, Kaminska MM, Baird NJ. Finely tuned conformational dynamics regulate the protective function of the lncRNA MALAT1 triple helix. Nucleic Acids Res 2019; 47:1468-1481. [PMID: 30462290 PMCID: PMC6379651 DOI: 10.1093/nar/gky1171] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/28/2018] [Accepted: 11/03/2018] [Indexed: 12/21/2022] Open
Abstract
Nucleic acid triplexes may regulate many important biological processes. Persistent accumulation of the oncogenic 7-kb long noncoding RNA MALAT1 is dependent on an unusually long intramolecular triple helix. This triplex structure is positioned within a conserved ENE (element for nuclear expression) motif at the lncRNA 3′ terminus and protects the entire transcript from degradation in a polyA-independent manner. A requisite 3′ maturation step leads to triplex formation though the precise mechanism of triplex folding remains unclear. Furthermore, the contributions of several peripheral structural elements to triplex formation and protective function have not been determined. We evaluated the stability, conformational fluctuations, and function of this MALAT1 ENE triple helix (M1TH) protective element using in vitro mutational analyses coupled with biochemical and biophysical characterizations. Using fluorescence and UV melts, FRET, and an exonucleolytic decay assay we define a concerted mechanism for triplex formation and uncover a metastable, dynamic triplex population under near-physiological conditions. Structural elements surrounding the triplex regulate the dynamic M1TH conformational variability, but increased triplex dynamics lead to M1TH degradation. Taken together, we suggest that finely tuned dynamics may be a general mechanism regulating triplex-mediated functions.
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Affiliation(s)
- Abeer A Ageeli
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA 19143, USA
| | | | - Magdalena M Kaminska
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA 19143, USA
| | - Nathan J Baird
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA 19143, USA
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26
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Abdollah-Nia F, Gelfand MP, Van Orden A. Three-State DNA Hairpin Conformational Dynamics Revealed by Higher-Order Fluorescence Correlation Spectroscopy. J Phys Chem B 2019; 123:1491-1504. [DOI: 10.1021/acs.jpcb.8b10703] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Butti Z, Patten SA. RNA Dysregulation in Amyotrophic Lateral Sclerosis. Front Genet 2019; 9:712. [PMID: 30723494 PMCID: PMC6349704 DOI: 10.3389/fgene.2018.00712] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 12/20/2018] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motor neuron disease and is characterized by the degeneration of upper and lower motor neurons. It has become increasingly clear that RNA dysregulation is a key contributor to ALS pathogenesis. The major ALS genes SOD1, TARDBP, FUS, and C9orf72 are involved in aspects of RNA metabolism processes such as mRNA transcription, alternative splicing, RNA transport, mRNA stabilization, and miRNA biogenesis. In this review, we highlight the current understanding of RNA dysregulation in ALS pathogenesis involving these major ALS genes and discuss the potential of therapeutic strategies targeting disease RNAs for treating ALS.
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Affiliation(s)
- Zoe Butti
- INRS-Institut Armand-Frappier, National Institute of Scientific Research, Laval, QC, Canada
| | - Shunmoogum A Patten
- INRS-Institut Armand-Frappier, National Institute of Scientific Research, Laval, QC, Canada
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28
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Mitchell ML, Leveille MP, Solecki RS, Tran T, Cannon B. Sequence-Dependent Effects of Monovalent Cations on the Structural Dynamics of Trinucleotide-Repeat DNA Hairpins. J Phys Chem B 2018; 122:11841-11851. [PMID: 30441902 DOI: 10.1021/acs.jpcb.8b07994] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Repetitive trinucleotide DNA sequences at specific genetic loci are associated with numerous hereditary, neurodegenerative diseases. The propensity of single-stranded domains containing these sequences to form secondary structure via extensive self-complementarity disrupts normal DNA processing to create genetic instabilities. To investigate these intrastrand structural dynamics, a DNA hairpin system was devised for single-molecule fluorescence study of the folding kinetics and energetics for secondary structure formation between two interacting, repetitive domains with specific numbers of the same trinucleotide motif (CXG), where X = T or A. Single-molecule fluorescence resonance energy transfer (smFRET) data show discrete conformational transitions between unstructured and closed hairpin states. The lifetimes of the closed hairpin states correlate with the number of repeats, with (CTG) N/(CTG) N domains maintaining longer-lived, closed states than equivalent-sized (CAG) N/(CAG) N domains. NaCl promotes similar degree of stabilization for the closed hairpin states of both repeat sequences. Temperature-based, smFRET experiments reveal that NaCl favors hairpin closing for (CAG) N/(CAG) N by preordering single-stranded repeat domains to accelerate the closing transition. In contrast, NaCl slows the opening transition of CTG hairpins; however, it promotes misfolded conformations that require unfolding. Energy diagrams illustrate the distinct folding pathways of (CTG) N and (CAG) N repeat domains and identify features that may contribute to their gene-destabilizing effects.
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Affiliation(s)
- Marisa L Mitchell
- Department of Physics , Loyola University Chicago , Chicago , Illinois 60660 , United States
| | - Michael P Leveille
- Department of Physics , Loyola University Chicago , Chicago , Illinois 60660 , United States
| | - Roman S Solecki
- Department of Physics , Loyola University Chicago , Chicago , Illinois 60660 , United States
| | - Thao Tran
- Department of Physics , Loyola University Chicago , Chicago , Illinois 60660 , United States
| | - Brian Cannon
- Department of Physics , Loyola University Chicago , Chicago , Illinois 60660 , United States
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29
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Monovalent ions modulate the flux through multiple folding pathways of an RNA pseudoknot. Proc Natl Acad Sci U S A 2018; 115:E7313-E7322. [PMID: 30012621 PMCID: PMC6077692 DOI: 10.1073/pnas.1717582115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The assembly mechanism of RNA, vital to describing its functions, depends on both the sequence and the metal ion concentration. How the latter influences the folding trajectories remains an important unsolved problem. Here, we examine the folding pathways of an RNA pseudoknot (PK) with key functional roles in transcription and translation, using a combination of experiments and simulations. We demonstrate that the PK, consisting of two hairpins with differing stabilities, folds by parallel pathways. Surprisingly, the flux between them is modulated by monovalent salt concentration. Our work shows that the order of assembly of PKs is determined by the relative stability of the hairpins, implying that the folding landscape can be controlled by sequence and ion concentration. The functions of RNA pseudoknots (PKs), which are minimal tertiary structural motifs and an integral part of several ribozymes and ribonucleoprotein complexes, are determined by their structure, stability, and dynamics. Therefore, it is important to elucidate the general principles governing their thermodynamics/folding mechanisms. Here, we combine laser temperature-jump experiments and coarse-grained simulations to determine the folding/unfolding pathways of VPK, a variant of the mouse mammary tumor virus (MMTV) PK involved in ribosomal frameshifting. Fluorescent nucleotide analogs (2-aminopurine and pyrrolocytidine) placed at different stem/loop positions in the PK serve as local probes allowing us to monitor the order of assembly of VPK that has two constituent hairpins with different intrinsic stabilities. We show that at 50 mM KCl, the dominant folding pathway populates only the more stable hairpin intermediate; as the salt concentration is increased, a parallel folding pathway emerges involving the less stable hairpin as an alternate intermediate. Notably, the flux between the pathways is modulated by the ionic strength. Our findings support the principle that the order of PK structure formation is determined by the relative stabilities of the hairpins, which can be altered by sequence variations or salt concentrations. The experimental results of salt effects on the partitioning between the two folding pathways are in remarkable agreement with simulations that were performed with no adjustable parameters. Our study not only unambiguously demonstrates that VPK folds by parallel pathways but also showcases the power of combining experiments and simulations for a more enriched description of RNA self-assembly.
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30
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Tran T, Cannon B. Differential Effects of Strand Asymmetry on the Energetics and Structural Flexibility of DNA Internal Loops. Biochemistry 2017; 56:6448-6459. [PMID: 29141138 DOI: 10.1021/acs.biochem.7b00930] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Internal loops within structured nucleic acids disrupt local base stacking and destabilize neighboring helical domains; however, these structural motifs also expand the conformational and functional capabilities of structured nucleic acids. Variations in the size, distribution of loop nucleotides on opposing strands (strand asymmetry), and sequence alter their biophysical properties. Here, the thermodynamics and structural flexibility of oligo-T-rich DNA internal loops were systematically investigated in terms of loop size and strand asymmetry. From optical melting experiments, a thermodynamic prediction model is proposed for the energetic penalty of internal loops that accounts for diminishing enthalpic and increasing entropic contributions due to loop size and strand asymmetry for bulges, asymmetric loops, and symmetric loops. These single-stranded domains become less sequence-dependent and more polymeric as the loop size increases. Single-molecule fluorescence resonance energy transfer studies reveal a gradual transition in conformation and structural flexibility from an elongated domain to an increasingly flexible bend that results from increasing strand asymmetry. The findings provide a framework for understanding the thermodynamic and conformational effects of internal loops for the rational design of functional DNA nanostructures.
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Affiliation(s)
- Thao Tran
- Department of Physics, Loyola University Chicago , Chicago, Illinois 60660, United States
| | - Brian Cannon
- Department of Physics, Loyola University Chicago , Chicago, Illinois 60660, United States
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31
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Lee HT, Carr CE, Khutsishvili I, Marky LA. Effect of Loop Length and Sequence on the Stability of DNA Pyrimidine Triplexes with TAT Base Triplets. J Phys Chem B 2017; 121:9175-9184. [PMID: 28875701 DOI: 10.1021/acs.jpcb.7b07591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the thermodynamic contributions of loop length and loop sequence to the overall stability of DNA intramolecular pyrimidine triplexes. Two sets of triplexes were designed: in the first set, the C5 loop closing the triplex stem was replaced with 5'-CTnC loops (n = 1-5), whereas in the second set, both the duplex and triplex loops were replaced with a 5'-GCAA or 5'-AACG tetraloop. For the triplexes with a 5'-CTnC loop, the triplex with five bases in the loop has the highest stability relative to the control. A loop length lower than five compromises the strength of the base-pair stacks without decreasing the thermal stability, leading to a decreased enthalpy, whereas an increase in the loop length leads to a decreased enthalpy and a higher entropic penalty. The incorporation of the GCAA loop yielded more stable triplexes, whereas the incorporation of AACG in the triplex loop yielded a less stable triplex due to an unfavorable enthalpy term. Thus, addition of the GCAA tetraloop can cause an increase in the thermodynamics of the triplex without affecting the sequence or melting behavior and may result in an additional layer of genetic regulation.
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Affiliation(s)
- Hui-Ting Lee
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Carolyn E Carr
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Irine Khutsishvili
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Luis A Marky
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
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32
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Mukherjee D, Bhattacharyya D. Intrinsic structural variability in GNRA-like tetraloops: insight from molecular dynamics simulation. J Mol Model 2017; 23:300. [DOI: 10.1007/s00894-017-3470-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 09/10/2017] [Indexed: 10/18/2022]
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33
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Shi YZ, Jin L, Wang FH, Zhu XL, Tan ZJ. Predicting 3D Structure, Flexibility, and Stability of RNA Hairpins in Monovalent and Divalent Ion Solutions. Biophys J 2016; 109:2654-2665. [PMID: 26682822 DOI: 10.1016/j.bpj.2015.11.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/09/2015] [Accepted: 11/06/2015] [Indexed: 10/24/2022] Open
Abstract
A full understanding of RNA-mediated biology would require the knowledge of three-dimensional (3D) structures, structural flexibility, and stability of RNAs. To predict RNA 3D structures and stability, we have previously proposed a three-bead coarse-grained predictive model with implicit salt/solvent potentials. In this study, we further develop the model by improving the implicit-salt electrostatic potential and including a sequence-dependent coaxial stacking potential to enable the model to simulate RNA 3D structure folding in divalent/monovalent ion solutions. The model presented here can predict 3D structures of RNA hairpins with bulges/internal loops (<77 nucleotides) from their sequences at the corresponding experimental ion conditions with an overall improved accuracy compared to the experimental data; the model also makes reliable predictions for the flexibility of RNA hairpins with bulge loops of different lengths at several divalent/monovalent ion conditions. In addition, the model successfully predicts the stability of RNA hairpins with various loops/stems in divalent/monovalent ion solutions.
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Affiliation(s)
- Ya-Zhou Shi
- Department of Physics and Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Lei Jin
- Department of Physics and Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Feng-Hua Wang
- Engineering Training Center, Jianghan University, Wuhan, China
| | - Xiao-Long Zhu
- Department of Physics, School of Physics and Information Engineering, Jianghan University, Wuhan, China
| | - Zhi-Jie Tan
- Department of Physics and Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
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34
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Cuypers L, Li G, Neumann-Haefelin C, Piampongsant S, Libin P, Van Laethem K, Vandamme AM, Theys K. Mapping the genomic diversity of HCV subtypes 1a and 1b: Implications of structural and immunological constraints for vaccine and drug development. Virus Evol 2016; 2:vew024. [PMID: 27774307 PMCID: PMC5072459 DOI: 10.1093/ve/vew024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Despite significant progress in hepatitis C (HCV) treatment, global viral eradication remains a challenge. An in-depth map of its genome diversity within the context of structural and immunological constraints could contribute to the design of pan-genotypic antivirals and preventive vaccines. For such analyses, extensive information is only available for the highly prevalent HCV genotypes (GT) 1a and 1b. Using 647 GT1a and 408 GT1b full-genome sequences obtained from the Los Alamos database, we found that respectively 3 per cent and 82 per cent of all codon positions are under positive and negative selective pressure, suggesting variation mainly accumulates due to random genetic drift. An association between conservation and both structured RNA and secondary protein structures confirmed the important role of structural elements at nucleotide and at amino acid level. Remarkably, CD8+ T-cell epitopes in HCV GT1a were significantly more conserved, while at the same time containing more sites under positive selection. Similarly, CD4+ T-cell epitopes were significantly more conserved in both HCV subtypes, but under less positive selective pressure in GT1b and more negative selective pressure in GT1a. In contrast, B-cell epitopes in both subtypes were less conserved and under less stringent negative selection. These findings argue against immune selective pressure as the main force of between-host diversifying evolution. Despite its high variability, HCV is under strict evolutionary constraints, most probably to keep its genes and proteins functional during the replication cycle. These are encouraging findings for vaccine and drug design, which could consider these newly established genetic diversity profiles.
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Affiliation(s)
- Lize Cuypers
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Guangdi Li
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium; Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, the Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Christoph Neumann-Haefelin
- Department of Medicine II, Freiburg University Medical Center, University of Freiburg, Freiburg, Germany
| | - Supinya Piampongsant
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium; Department of Electrical Engineering ESAT, STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven, University of Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee, Belgium
| | - Pieter Libin
- Artificial Intelligence Lab, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Kristel Van Laethem
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium
| | - Anne-Mieke Vandamme
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium; Center for Global Health and Tropical Medicine, Microbiology Unit, Institute for Hygiene and Tropical Medicine, University Nova de Lisboa, Rua da Junqueira 100, Lisbon, 1349-008, Portugal
| | - Kristof Theys
- KU Leuven, University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Clinical and Epidemiological Virology, Minderbroedersstraat 10, 3000 Leuven, Belgium
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35
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Chakraborty K, Khatua P, Bandyopadhyay S. Exploring ion induced folding of a single-stranded DNA oligomer from molecular simulation studies. Phys Chem Chem Phys 2016; 18:15899-910. [PMID: 27241311 DOI: 10.1039/c6cp00663a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
One crucial issue in DNA hydration is the effect of salts on its conformational features. This has relevance in biology as cations present in the cellular environment shield the negative charges on the DNA backbone, thereby reducing the repulsive force between them. By screening the negative charges along the backbone, cations stabilize the folded structure of DNA. To study the effect of the added salt on single-stranded DNA (ss-DNA) conformations, we have performed room temperature molecular dynamics simulations of an aqueous solution containing the ss-DNA dodecamer with the 5'-CGCGAATTCGCG-3' sequence in the presence of 0.2, 0.5, and 0.8 M NaCl. Our calculations reveal that in the presence of the salt, the DNA molecule forms more collapsed coil-like conformations due to the screening of negative charges along the backbone. Additionally, we demonstrated that the formation of an octahedral inner-sphere complex by the strongly bound ion plays an important role in the stabilization of such folded conformation of DNA. Importantly, it is found that ion-DNA interactions can also explain the formation of non-sequential base stackings with longer lifetimes. Such non-sequential base stackings further stabilize the collapsed coil-like folded form of the DNA oligomer.
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Affiliation(s)
- Kaushik Chakraborty
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur - 721302, India.
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36
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Jabasini M, Ewis A, Sato Y, Nakahori Y, Baba Y. Anomalous Separation of Small Y-Chromosomal DNA Fragments on Microchip Electrophoresis. Sci Pharm 2016; 84:507-513. [PMID: 28117316 PMCID: PMC5064241 DOI: 10.3390/scipharm84030507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/13/2016] [Indexed: 11/16/2022] Open
Abstract
We investigated an anomalous DNA separation where two DNA fragments from the human Y-chromosome sY638 (64 bp) and sY592 (65 bp), with only one base pair difference, were separated. This result is abnormal since in a previous study, we found that 5 bp was the minimum difference between two DNA fragments that the microchip electrophoresis system can separate. The formation of a mini-loop in the structure of the DNA fragment of sY638 (64 bp) was strongly expected to be the reason. To investigate this, we synthesized three modified DNA fragments for sY638 (64 bp), and the modifications were in two expected locations for possible mini-loop formation. Later, the separation between sY592 (65 bp) and the three modified fragments of sY638 (64 bp) was not possible. Thus, we conclude that the formation of a mini-loop in the structure of the DNA is the reason behind this anomalous separation.
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Affiliation(s)
- Mohammad Jabasini
- Department of Pharmaceutical Information Science, Institute of Health Biosciences, The University of Tokushima, 1-78-1 Sho-machi, 770-8505 Tokushima, Japan.
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, 464-8603 Nagoya, Japan.
| | - Ashraf Ewis
- Department of Human Genetics Public Health, School of Medicine, The University of Tokushima, 3-18-15 Kuramoto-cho, 770-8503 Tokushima, Japan.
| | - Youichi Sato
- Department of Pharmaceutical Information Science, Institute of Health Biosciences, The University of Tokushima, 1-78-1 Sho-machi, 770-8505 Tokushima, Japan.
| | - Yutaka Nakahori
- Department of Human Genetics Public Health, School of Medicine, The University of Tokushima, 3-18-15 Kuramoto-cho, 770-8503 Tokushima, Japan.
| | - Yoshinobu Baba
- Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, 464-8603 Nagoya, Japan.
- ImPACT Research Center for Advanced Nanobiodevices., Nagoya University, Furo-cho, Chikusa-ku, 464-8603 Nagoya, Japan.
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, 761-0395 Takamatsu, Japan.
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37
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Miller MT, Tuske S, Das K, DeStefano JJ, Arnold E. Structure of HIV-1 reverse transcriptase bound to a novel 38-mer hairpin template-primer DNA aptamer. Protein Sci 2015; 25:46-55. [PMID: 26296781 DOI: 10.1002/pro.2776] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 08/19/2015] [Accepted: 08/20/2015] [Indexed: 01/09/2023]
Abstract
The development of a modified DNA aptamer that binds HIV-1 reverse transcriptase (RT) with ultra-high affinity has enabled the X-ray structure determination of an HIV-1 RT-DNA complex to 2.3 Å resolution without the need for an antibody Fab fragment or RT-DNA cross-linking. The 38-mer hairpin-DNA aptamer has a 15 base-pair duplex, a three-deoxythymidine hairpin loop, and a five-nucleotide 5'-overhang. The aptamer binds RT in a template-primer configuration with the 3'-end positioned at the polymerase active site and has 2'-O-methyl modifications at the second and fourth duplex template nucleotides that interact with the p66 fingers and palm subdomains. This structure represents the highest resolution RT-nucleic acid structure to date. The RT-aptamer complex is catalytically active and can serve as a platform for studying fundamental RT mechanisms and for development of anti-HIV inhibitors through fragment screening and other approaches. Additionally, the structure allows for a detailed look at a unique aptamer design and provides the molecular basis for its remarkably high affinity for RT.
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Affiliation(s)
- Matthew T Miller
- Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, 08854
| | - Steve Tuske
- Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, 08854
| | - Kalyan Das
- Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, 08854
| | - Jeffrey J DeStefano
- Department of Cell Biology and Molecular Genetics, University of Maryland College Park, College Park, Maryland, 20742
| | - Eddy Arnold
- Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, 08854
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38
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Ghosh S, Dixit H, Chakrabarti R. Ion assisted structural collapse of a single stranded DNA: A molecular dynamics approach. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.07.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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39
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Hoynes-O'Connor A, Hinman K, Kirchner L, Moon TS. De novo design of heat-repressible RNA thermosensors in E. coli. Nucleic Acids Res 2015; 43:6166-79. [PMID: 25979263 PMCID: PMC4499127 DOI: 10.1093/nar/gkv499] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 05/04/2015] [Indexed: 11/15/2022] Open
Abstract
RNA-based temperature sensing is common in bacteria that live in fluctuating environments. Most naturally-occurring RNA thermosensors are heat-inducible, have long sequences, and function by sequestering the ribosome binding site in a hairpin structure at lower temperatures. Here, we demonstrate the de novo design of short, heat-repressible RNA thermosensors. These thermosensors contain a cleavage site for RNase E, an enzyme native to Escherichia coli and many other organisms, in the 5′ untranslated region of the target gene. At low temperatures, the cleavage site is sequestered in a stem–loop, and gene expression is unobstructed. At high temperatures, the stem–loop unfolds, allowing for mRNA degradation and turning off expression. We demonstrated that these thermosensors respond specifically to temperature and provided experimental support for the central role of RNase E in the mechanism. We also demonstrated the modularity of these RNA thermosensors by constructing a three-input composite circuit that utilizes transcriptional, post-transcriptional, and post-translational regulation. A thorough analysis of the 24 thermosensors allowed for the development of design guidelines for systematic construction of similar thermosensors in future applications. These short, modular RNA thermosensors can be applied to the construction of complex genetic circuits, facilitating rational reprogramming of cellular processes for synthetic biology applications.
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Affiliation(s)
- Allison Hoynes-O'Connor
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Kristina Hinman
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Lukas Kirchner
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Tae Seok Moon
- Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
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40
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Melnykov AV, Nayak RK, Hall KB, Van Orden A. Effect of loop composition on the stability and folding kinetics of RNA hairpins with large loops. Biochemistry 2015; 54:1886-96. [PMID: 25697574 DOI: 10.1021/bi5014276] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RNA hairpins are ubiquitous structural elements in biological RNAs, where they have the potential to regulate RNA folding and interactions with other molecules. There are established methods for predicting the thermodynamic stability of an RNA hairpin, but there are still relatively few detailed examinations of the kinetics of folding. Nonetheless, several recent studies indicate that hairpin folding does not proceed via a simple two-state model. Here, we monitor fluorescence from hairpins constructed as molecular beacons in ensemble, fluorescence correlation spectroscopy, and stopped-flow experiments to describe the folding of RNA hairpins with long (15 nucleotide) loops. Our results show that folding of these hairpins occurs through more than two states and that the mechanism of folding includes a fast intermediate phase observed on the tens of microseconds time scale and a slow phase, attributed to formation of the native folded hairpin loop and stem, observed on the milliseconds time scale. The composition of the RNA loop determines the time scale of intermediate and native folded states. Hairpins with a polyuracil loop sequence exhibit slower relaxation of the intermediate state and faster relaxation of the native folded state when compared to that of hairpins with cytosine or adenine in the loop. We hypothesize this composition dependence could be attributed to nucleobase stacking in cytosine and adenine containing regions of the loop, which would be absent in hairpins containing polyuracil loops. Such base stacking could destabilize the intermediate folds, thereby speeding the relaxation of the intermediate relative to similar sized hairpins with no base stacking in the loop. Likewise, the lower intermediate stability could prolong the relaxation of the native folded state.
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Affiliation(s)
- Artem V Melnykov
- †Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Rajesh K Nayak
- ‡Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Kathleen B Hall
- †Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Alan Van Orden
- ‡Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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41
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Reilly SM, Morgan RK, Brooks TA, Wadkins RM. Effect of interior loop length on the thermal stability and pK(a) of i-motif DNA. Biochemistry 2015; 54:1364-70. [PMID: 25619229 DOI: 10.1021/bi5014722] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The four-stranded i-motif (iM) conformation of cytosine-rich DNA is important in a wide variety of biochemical systems ranging from its use in nanomaterials to a potential role in oncogene regulation. An iM is stabilized by acidic pH that allows hemiprotonated cytidines to form a C·C(+) base pair. Fundamental studies that aim to understand how the lengths of loops connecting the protonated C·C(+) pairs affect intramolecular iM physical properties are described here. We characterized both the thermal stability and the pK(a) of intramolecular iMs with differing loop lengths, in both dilute solutions and solutions containing molecular crowding agents. Our results showed that intramolecular iMs with longer central loops form at pHs and temperatures higher than those of iMs with longer outer loops. Our studies also showed that increases in thermal stability of iMs when molecular crowding agents are present are dependent on the loop that is lengthened. However, the increase in pK(a) for iMs when molecular crowding agents are present is insensitive to loop length. Importantly, we also determined the proton activity of solutions containing high concentrations of molecular crowding agents to ascertain whether the increase in pK(a) of an iM is caused by alteration of this activity in buffered solutions. We determined that crowding agents alone increase the apparent pK(a) of a number of small molecules as well as iMs but that increases to iM pK(a) were greater than that expected from a shift in proton activity.
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Affiliation(s)
- Samantha M Reilly
- Department of Chemistry and Biochemistry, University of Mississippi , University, Mississippi 38677, United States
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42
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Chen X, Velmurugu Y, Zheng G, Park B, Shim Y, Kim Y, Liu L, Van Houten B, He C, Ansari A, Min JH. Kinetic gating mechanism of DNA damage recognition by Rad4/XPC. Nat Commun 2015; 6:5849. [PMID: 25562780 PMCID: PMC4354021 DOI: 10.1038/ncomms6849] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 11/13/2014] [Indexed: 01/24/2023] Open
Abstract
The xeroderma pigmentosum C (XPC) complex initiates nucleotide excision repair by recognizing DNA lesions before recruiting downstream factors. How XPC detects structurally diverse lesions embedded within normal DNA is unknown. Here we present a crystal structure that captures the yeast XPC orthologue (Rad4) on a single register of undamaged DNA. The structure shows that a disulphide-tethered Rad4 flips out normal nucleotides and adopts a conformation similar to that seen with damaged DNA. Contrary to many DNA repair enzymes that can directly reject non-target sites as structural misfits, our results suggest that Rad4/XPC uses a kinetic gating mechanism whereby lesion selectivity arises from the kinetic competition between DNA opening and the residence time of Rad4/XPC per site. This mechanism is further supported by measurements of Rad4-induced lesion-opening times using temperature-jump perturbation spectroscopy. Kinetic gating may be a general mechanism used by site-specific DNA-binding proteins to minimize time-consuming interrogations of non-target sites. XPC nucleotide excision repair factor is key to starting the repair of diverse helix-distorting DNA lesions caused by environmental insults. Here, the authors propose a kinetic gating mechanism whereby XPC recognizes DNA lesions by preferentially opening damaged sites while readily diffusing away from undamaged sites.
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Affiliation(s)
- Xuejing Chen
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
| | - Yogambigai Velmurugu
- Department of Physics, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
| | - Guanqun Zheng
- Department of Chemistry, Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
| | - Beomseok Park
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
| | - Yoonjung Shim
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
| | - Youngchang Kim
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA
| | - Lili Liu
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine and University of Pittsburgh Cancer Institute, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, Pennsylvania 15213, USA
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine and University of Pittsburgh Cancer Institute, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, Pennsylvania 15213, USA
| | - Chuan He
- Department of Chemistry, Institute for Biophysical Dynamics, The University of Chicago, 929 E. 57th Street, Chicago, Illinois 60637, USA
| | - Anjum Ansari
- 1] Department of Physics, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA [2] Department of Bioengineering, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
| | - Jung-Hyun Min
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, Illinois 60607, USA
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43
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RNA folding: structure prediction, folding kinetics and ion electrostatics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 827:143-83. [PMID: 25387965 DOI: 10.1007/978-94-017-9245-5_11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Beyond the "traditional" functions such as gene storage, transport and protein synthesis, recent discoveries reveal that RNAs have important "new" biological functions including the RNA silence and gene regulation of riboswitch. Such functions of noncoding RNAs are strongly coupled to the RNA structures and proper structure change, which naturally leads to the RNA folding problem including structure prediction and folding kinetics. Due to the polyanionic nature of RNAs, RNA folding structure, stability and kinetics are strongly coupled to the ion condition of solution. The main focus of this chapter is to review the recent progress in the three major aspects in RNA folding problem: structure prediction, folding kinetics and ion electrostatics. This chapter will introduce both the recent experimental and theoretical progress, while emphasize the theoretical modelling on the three aspects in RNA folding.
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44
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Polinkovsky ME, Gambin Y, Banerjee PR, Erickstad MJ, Groisman A, Deniz AA. Ultrafast cooling reveals microsecond-scale biomolecular dynamics. Nat Commun 2014; 5:5737. [DOI: 10.1038/ncomms6737] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 11/03/2014] [Indexed: 11/09/2022] Open
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45
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Chen J, Poddar NK, Tauzin LJ, Cooper D, Kolomeisky AB, Landes CF. Single-molecule FRET studies of HIV TAR-DNA hairpin unfolding dynamics. J Phys Chem B 2014; 118:12130-9. [PMID: 25254491 PMCID: PMC4207534 DOI: 10.1021/jp507067p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We directly measure the dynamics of the HIV trans-activation response (TAR)-DNA hairpin with multiple loops using single-molecule Förster resonance energy transfer (smFRET) methods. Multiple FRET states are identified that correspond to intermediate melting states of the hairpin. The stability of each intermediate state is calculated from the smFRET data. The results indicate that hairpin unfolding obeys a "fraying and peeling" mechanism, and evidence for the collapse of the ends of the hairpin during folding is observed. These results suggest a possible biological function for hairpin loops serving as additional fraying centers to increase unfolding rates in otherwise stable systems. The experimental and analytical approaches developed in this article provide useful tools for studying the mechanism of multistate DNA hairpin dynamics and of other general systems with multiple parallel pathways of chemical reactions.
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Affiliation(s)
- Jixin Chen
- Department of Chemistry and ‡Department of Electrical and Computer Engineering, Rice University , Houston, Texas 77251-1892, United States
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46
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Chakraborty K, Mantha S, Bandyopadhyay S. Molecular dynamics simulation of a single-stranded DNA with heterogeneous distribution of nucleobases in aqueous medium. J Chem Phys 2014; 139:075103. [PMID: 23968115 DOI: 10.1063/1.4818537] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The DNA metabolic processes often involve single-stranded DNA (ss-DNA) molecules as important intermediates. In the absence of base complementarity, ss-DNAs are more flexible and interact strongly with water in aqueous media. Ss-DNA-water interactions are expected to control the conformational flexibility of the DNA strand, which in turn should influence the properties of the surrounding water molecules. We have performed room temperature molecular dynamics simulation of an aqueous solution containing the ss-DNA dodecamer, 5'-CGCGAATTCGCG-3'. The conformational flexibility of the DNA strand and the microscopic structure and ordering of water molecules around it have been explored. The simulation reveals transformation of the initial base-stacked form of the ss-DNA to a fluctuating collapsed coil-like conformation with the formation of a few non-sequentially stacked base pairs. A preliminary analysis shows further collapse of the DNA conformation in presence of additional salt (NaCl) due to screening of negative charges along the backbone by excess cations. Additionally, higher packing of water molecules within a short distance from the DNA strand is found to be associated with realignment of water molecules by breaking their regular tetrahedral ordering.
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Affiliation(s)
- Kaushik Chakraborty
- Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India
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47
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Völker J, Plum GE, Gindikin V, Klump HH, Breslauer KJ. Impact of bulge loop size on DNA triplet repeat domains: Implications for DNA repair and expansion. Biopolymers 2014; 101:1-12. [PMID: 23494673 PMCID: PMC3920904 DOI: 10.1002/bip.22236] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 03/05/2013] [Indexed: 11/12/2022]
Abstract
Repetitive DNA sequences exhibit complex structural and energy landscapes, populated by metastable, noncanonical states, that favor expansion and deletion events correlated with disease phenotypes. To probe the origins of such genotype-phenotype linkages, we report the impact of sequence and repeat number on properties of (CNG) repeat bulge loops. We find the stability of duplexes with a repeat bulge loop is controlled by two opposing effects; a loop junction-dependent destabilization of the underlying double helix, and a self-structure dependent stabilization of the repeat bulge loop. For small bulge loops, destabilization of the underlying double helix overwhelms any favorable contribution from loop self-structure. As bulge loop size increases, the stabilizing loop structure contribution dominates. The role of sequence on repeat loop stability can be understood in terms of its impact on the opposing influences of junction formation and loop structure. The nature of the bulge loop affects the thermodynamics of these two contributions differently, resulting in unique differences in repeat size-dependent minima in the overall enthalpy, entropy, and free energy changes. Our results define factors that control repeat bulge loop formation; knowledge required to understand how this helix imperfection is linked to DNA expansion, deletion, and disease phenotypes.
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Affiliation(s)
- Jens Völker
- Department of Chemistry and Chemical Biology, Rutgers, The
State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
| | - G. Eric Plum
- IBET, Inc., 1507 Chambers Road, Suite 301, Columbus, OH
43212
| | - Vera Gindikin
- Department of Chemistry and Chemical Biology, Rutgers, The
State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
| | - Horst H. Klump
- Department of Molecular and Cell Biology,
University of Cape Town, Private Bag, Rondebosch 7800, South Africa
| | - Kenneth J. Breslauer
- Department of Chemistry and Chemical Biology, Rutgers, The
State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
- The Cancer Institute of New Jersey, New Brunswick,
NJ 08901
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48
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Tsukanov R, Tomov TE, Berger Y, Liber M, Nir E. Conformational Dynamics of DNA Hairpins at Millisecond Resolution Obtained from Analysis of Single-Molecule FRET Histograms. J Phys Chem B 2013; 117:16105-9. [DOI: 10.1021/jp411280n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Roman Tsukanov
- Department of Chemistry
and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Toma E. Tomov
- Department of Chemistry
and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Yaron Berger
- Department of Chemistry
and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Miran Liber
- Department of Chemistry
and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Eyal Nir
- Department of Chemistry
and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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49
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Xia T, Yuan J, Fang X. Conformational dynamics of an ATP-binding DNA aptamer: a single-molecule study. J Phys Chem B 2013; 117:14994-5003. [PMID: 24245799 DOI: 10.1021/jp4099667] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nucleic acid aptamers are single-stranded RNA or DNA molecules that bind to their targets with high specificity and affinity. Although their biomedical applications have been booming, it is still debatable whether an aptamer recognizes its target through "induced fit" or "conformational selection", a central question in molecular recognition. To address this question, an ATP-binding DNA aptamer was selected as a model system and the conformational properties of this aptamer with and without the presence of ATP were investigated by single-pair Förster resonance energy transfer (spFRET) spectroscopy. The single-molecule results indicate that the aptamer can fold into a double-stranded-like structure, similar to the ligand-bound conformation, even without the presence of ATP. The folded structure is thermally stable at high salt concentrations and becomes rather dynamic at low salt concentrations. Although in the latter condition, the aptamer prefers unfolded structures, it can occasionally migrate to the folded conformation for a short time before being unfolded again. The binding of ATP to the aptamer stabilizes the folded structure, which populates the ligand-bound state of the aptamer, thus shifting the conformational equilibrium. Collectively, our data support that the ATP-binding DNA aptamer recognizes ATP ligand through "conformational selection".
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Affiliation(s)
- Tie Xia
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Key Laboratory of Molecular Nanostructure and Nanotechnology, Chinese Academy of Sciences , Beijing 100190, P. R. China
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50
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Nayak RK, Van Orden A. Counterion and polythymidine loop-length-dependent folding and thermodynamic stability of DNA hairpins reveal the unusual counterion-dependent stability of tetraloop hairpins. J Phys Chem B 2013; 117:13956-66. [PMID: 24144397 DOI: 10.1021/jp404832d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Stem-loop DNA hairpins containing a 5-base-pair (bp) stem and single-stranded polythymidine loop were investigated using thermodynamic melting analysis and stopped-flow kinetics. These studies revealed the thermodynamic stability and folding kinetics as a function of loop length and counterion concentration. Our results show the unusually high thermodynamic stability for tetraloop or 4 poly(dT) loop hairpin as compared with longer loop length hairpins. Furthermore, this exceptional stability is highly counterion-dependent. For example, in the higher counterion concentration regime of 50 mM NaCl and above, the tetraloop hairpin displays enhanced stability as compared with longer loop length hairpins. However, at lower counterion concentration of 25 mM NaCl and below, the thermal stability of tetraloop hairpin is consistent with the longer loop hairpins. The enhanced stability of tetraloop hairpins at higher counterion concentration can be explained on the basis of the combined entropic effect of loop closure as well as base stacking in the loop regions. The stability of longer loop length hairpins at all counterion concentrations as well as tetraloop hairpin at lower counterion concentration can be explained on the basis of entropic effect of loop closure alone. The thermodynamic parameters at lower and higher counterion concentrations were determined to quantify the enhanced stability of base-stacking effects occurring at higher counterion concentrations. For example, for 100 mM NaCl, excess Gibbs energy and enthalpy due to base stacking within the tetraloops were measured to be -1.2 ± 0.14 and -3.28 ± 0.32 kcal/mol, respectively, whereas, no excess of Gibbs energy and enthalpy was observed for 0, 5, 10, and 25 mM NaCl. These findings suggest significant base-stacking interactions occurring in the loop region of the tetraloop hairpins at higher counterion concentration and less significant base-stacking interactions in the lower counterion concentration regime. We suggest that at higher counterion concentrations, hydrophobic collapse of the nucleotides in the loop may be enhanced due to the increased polarity of the solvent, thereby enhancing base-stacking interactions that contribute to unusually high stability.
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Affiliation(s)
- Rajesh K Nayak
- Department of Chemistry, Colorado State University , Fort Collins, Colorado 80523, United States
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