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Halder S, Thakur A, Keshry SS, Jana P, Karothia D, Das Jana I, Acevedo O, Swain RK, Mondal A, Chattopadhyay S, Jayaprakash V, Dev A. SELEX based aptamers with diagnostic and entry inhibitor therapeutic potential for SARS-CoV-2. Sci Rep 2023; 13:14560. [PMID: 37666993 PMCID: PMC10477244 DOI: 10.1038/s41598-023-41885-w] [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: 06/23/2023] [Accepted: 09/01/2023] [Indexed: 09/06/2023] Open
Abstract
Frequent mutation and variable immunological protection against vaccination is a common feature for COVID-19 pandemic. Early detection and confinement remain key to controlling further spread of infection. In response, we have developed an aptamer-based system that possesses both diagnostic and therapeutic potential towards the virus. A random aptamer library (~ 1017 molecules) was screened using systematic evolution of ligands by exponential enrichment (SELEX) and aptamer R was identified as a potent binder for the SARS-CoV-2 spike receptor binding domain (RBD) using in vitro binding assay. Using a pseudotyped viral entry assay we have shown that aptamer R specifically inhibited the entry of a SARS-CoV-2 pseudotyped virus in HEK293T-ACE2 cells but did not inhibit the entry of a Vesicular Stomatitis Virus (VSV) glycoprotein (G) pseudotyped virus, hence establishing its specificity towards SARS-CoV-2 spike protein. The antiviral potential of aptamers R and J (same central sequence as R but lacking flanked primer regions) was tested and showed 95.4% and 82.5% inhibition, respectively, against the SARS-CoV-2 virus. Finally, intermolecular interactions between the aptamers and the RBD domain were analyzed using in silico docking and molecular dynamics simulations that provided additional insight into the binding and inhibitory action of aptamers R and J.
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Affiliation(s)
- Sayanti Halder
- Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
| | - Abhishek Thakur
- Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA
| | - Supriya Suman Keshry
- Institute of Life Sciences, Bhubaneswar, Odisha, 751023, India
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, Odisha, India
| | - Pradip Jana
- Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
| | | | - Indrani Das Jana
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | - Orlando Acevedo
- Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA
| | - Rajeeb K Swain
- Institute of Life Sciences, Bhubaneswar, Odisha, 751023, India
| | - Arindam Mondal
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India
| | | | - Venkatesan Jayaprakash
- Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India
| | - Abhimanyu Dev
- Department of Pharmaceutical Sciences and Technology, Birla Institute of Technology, Mesra, Ranchi, Jharkhand, 835215, India.
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Mariottini D, Idili A, Ercolani G, Ricci F. Thermo-Programmed Synthetic DNA-Based Receptors. ACS NANO 2023; 17:1998-2006. [PMID: 36689298 PMCID: PMC9933611 DOI: 10.1021/acsnano.2c07039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
Herein, we present a generalizable and versatile strategy to engineer synthetic DNA ligand-binding devices that can be programmed to load and release a specific ligand at a defined temperature. We do so by re-engineering two model DNA-based receptors: a triplex-forming bivalent DNA-based receptor that recognizes a specific DNA sequence and an ATP-binding aptamer. The temperature at which these receptors load/release their ligands can be finely modulated by controlling the entropy associated with the linker connecting the two ligand-binding domains. The availability of a set of receptors with tunable and reversible temperature dependence allows achieving complex load/release behavior such as sustained ligand release over a wide temperature range. Similar programmable thermo-responsive synthetic ligand-binding devices can be of utility in applications such as drug delivery and production of smart materials.
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Affiliation(s)
- Davide Mariottini
- Chemistry
Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Andrea Idili
- Chemistry
Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Gianfranco Ercolani
- Chemistry
Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Francesco Ricci
- Chemistry
Department, University of Rome, Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
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3
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Kensinger AH, Makowski JA, Pellegrene KA, Imperatore JA, Cunningham CL, Frye CJ, Lackey PE, Mihailescu MR, Evanseck JD. Structural, Dynamical, and Entropic Differences between SARS-CoV and SARS-CoV-2 s2m Elements Using Molecular Dynamics Simulations. ACS PHYSICAL CHEMISTRY AU 2023; 3:30-43. [PMID: 36711027 PMCID: PMC9578647 DOI: 10.1021/acsphyschemau.2c00032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/21/2022] [Accepted: 09/21/2022] [Indexed: 11/05/2022]
Abstract
The functional role of the highly conserved stem-loop II motif (s2m) in SARS-CoV and SARS-CoV-2 in the viral lifecycle remains enigmatic and an intense area of research. Structure and dynamics of the s2m are key to establishing a structure-function connection, yet a full set of atomistic resolution coordinates is not available for SARS-CoV-2 s2m. Our work constructs three-dimensional coordinates consistent with NMR solution phase data for SARS-CoV-2 s2m and provides a comparative analysis with its counterpart SARS-CoV s2m. We employed initial coordinates based on PDB ID 1XJR for SARS-CoV s2m and two models for SARS-CoV-2 s2m: one based on 1XJR in which we introduced the mutations present in SARS-CoV-2 s2m and the second based on the available SARS-CoV-2 NMR NOE data supplemented with knowledge-based methods. For each of the three systems, 3.5 μs molecular dynamics simulations were used to sample the structure and dynamics, and principal component analysis (PCA) reduced the ensembles to hierarchal conformational substates for detailed analysis. Dilute solution simulations of SARS-CoV s2m demonstrate that the GNRA-like terminal pentaloop is rigidly defined by base stacking uniquely positioned for possible kissing dimer formation. However, the SARS-CoV-2 s2m simulation did not retain the reported crystallographic SARS-CoV motifs and the terminal loop expands to a highly dynamic "nonaloop." Increased flexibility and structural disorganization are observed for the larger terminal loop, where an entropic penalty is computed to explain the experimentally observed reduction in kissing complex formation. Overall, both SARS-CoV and SARS-CoV-2 s2m elements have a similarly pronounced L-shape due to different motif interactions. Our study establishes the atomistic three-dimensional structure and uncovers dynamic differences that arise from s2m sequence changes, which sets the stage for the interrogation of different mechanistic pathways of suspected biological function.
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Affiliation(s)
- Adam H. Kensinger
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Joseph A. Makowski
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Kendy A. Pellegrene
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Joshua A. Imperatore
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Caylee L. Cunningham
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Caleb J. Frye
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Patrick E. Lackey
- Department
of Biochemistry and Chemistry, Westminster
College, New Wilmington, Pennsylvania16172, United States
| | - Mihaela Rita Mihailescu
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
| | - Jeffrey D. Evanseck
- Department
of Chemistry and Biochemistry and Center for Computational Sciences, Duquesne University, Pittsburgh, Pennsylvania15282, United States
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4
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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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Cheng Y, Zhang S, Xu X, Chen SJ. Vfold2D-MC: A Physics-Based Hybrid Model for Predicting RNA Secondary Structure Folding. J Phys Chem B 2021; 125:10108-10118. [PMID: 34473508 DOI: 10.1021/acs.jpcb.1c04731] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accurate prediction of RNA structure and folding stability has a far-reaching impact on our understanding of RNA functions. Here we develop Vfold2D-MC, a new physics-based model, to predict RNA structure and folding thermodynamics from the sequence. The model employs virtual bond-based coarse-graining of RNA backbone conformation and generates RNA conformations through Monte Carlo sampling of the bond angles and torsional angles of the virtual bonds. Using a coarse-grained statistical potential derived from the known structures, we assign each conformation with a statistical weight. The weighted average over the conformational ensemble gives the entropy and free energy parameters for the hairpin, bulge, and internal loops, and multiway junctions. From the thermodynamic parameters, we predict RNA structures, melting curves, and structural changes from the sequence. Theory-experiment comparisons indicate that Vfold2D-MC not only gives improved structure predictions but also enables the interpretation of thermodynamic results for different RNA structures, including multibranched junctions. This new model sets a promising framework to treat more complicated RNA structures, such as pseudoknotted and intramolecular kissing loops, for which experimental thermodynamic parameters are often unavailable.
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Affiliation(s)
- Yi Cheng
- Department of Physics, Department of Biochemistry, and Institute for Data Science and Informatics, University of Missouri, Columbia, Missouri 65211, United States
| | - Sicheng Zhang
- Department of Physics, Department of Biochemistry, and Institute for Data Science and Informatics, University of Missouri, Columbia, Missouri 65211, United States
| | - Xiaojun Xu
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou, Jiangsu 213001, China
| | - Shi-Jie Chen
- Department of Physics, Department of Biochemistry, and Institute for Data Science and Informatics, University of Missouri, Columbia, Missouri 65211, United States
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Mak CH, Phan ENH. Diagrammatic approaches to RNA structures with trinucleotide repeats. Biophys J 2021; 120:2343-2354. [PMID: 33887227 PMCID: PMC8390803 DOI: 10.1016/j.bpj.2021.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 04/07/2021] [Accepted: 04/09/2021] [Indexed: 11/30/2022] Open
Abstract
Trinucleotide repeat expansion disorders are associated with the overexpansion of (CNG) repeats on the genome. Messenger RNA transcripts of sequences with greater than 60–100 (CNG) tandem units have been implicated in trinucleotide repeat expansion disorder pathogenesis. In this work, we develop a diagrammatic theory to study the structural diversity of these (CNG)n RNA sequences. Representing structural elements on the chain’s conformation by a set of graphs and employing elementary diagrammatic methods, we have formulated a renormalization procedure to re-sum these graphs and arrive at a closed-form expression for the ensemble partition function. With a simple approximation for the renormalization and applied to extended (CNG)n sequences, this theory can comprehensively capture an infinite set of conformations with any number and any combination of duplexes, hairpins, multiway junctions, and quadruplexes. To quantify the diversity of different (CNG)n ensembles, the analytical equations derived from the diagrammatic theory were solved numerically to derive equilibrium estimates for the secondary structural contents of the chains. The results suggest that the structural ensembles of (CNG)n repeat sequence with n ∼60 are surprisingly diverse, and the distribution is sensitive to the ability of the N nucleotide to make noncanonical pairs and whether the (CNG)n sequence can sustain stable quadruplexes. The results show how perturbations in the form of biases on the stabilities of the various structural motifs, duplexes, junctions, helices, and quadruplexes could affect the secondary structures of the chains and how these structures may switch when they are perturbed.
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Affiliation(s)
- Chi H Mak
- Department of Chemistry, Center of Applied Mathematical Sciences and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California.
| | - Ethan N H Phan
- Department of Chemistry, University of Southern California, Los Angeles, California
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Mak CH. Theoretical Model for Solvent-Induced Base Stacking Interactions in Solvent-Free DNA Simulations. J Phys Chem B 2019; 123:1939-1949. [PMID: 30727734 DOI: 10.1021/acs.jpcb.8b10848] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ultrahigh-throughput conformational sampling of biopolymers like nucleic acids are most effectively carried out without explicit solvents, but the physical origins of almost all inter- and intramolecular interactions controlling nucleic acid structures are rooted in water. Single-stranded (ss) DNAs or RNAs in water are characterized by ensembles of diverse conformations. To properly capture solvent-induced nucleobase stacking interactions in an otherwise solvent-free Monte Carlo algorithm, theoretical models are developed here to describe the solvent entropy and dispersion terms in base stacking free energies. To validate these models, equilibrium ensembles of ss (dA) n and (dT) n sequences ( n = 30, 40, and 50) were simulated, and they quantitatively reproduced experimental small-angle X-ray scattering (SAXS) data. Simulated dA ensembles show substantial stacking. While less prevalent, stacking in dT chains is not negligible. Analysis of SAXS profiles suggests that excess features between wavevector 0.03 and 0.18 Å-1 correlate with stacking, and stacking in dA versus dT chains is chain length-dependent, where (dT)30 and (dA)30 chains have more similar structures, but longer dA chains show more stacking over dT. The average stack length in ss-dA chains is 5-10 nucleotides, yielding an estimate for the overall A|A stacking free energy at ∼1 kcal/mol.
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Affiliation(s)
- Chi H Mak
- Departments of Chemistry and Biological Sciences, and Center of Applied Mathematical Sciences , University of Southern California , Los Angeles , California 90089 , United States
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Mariottini D, Idili A, Nijenhuis MAD, de Greef TFA, Ricci F. DNA-Based Nanodevices Controlled by Purely Entropic Linker Domains. J Am Chem Soc 2018; 140:14725-14734. [PMID: 30351025 DOI: 10.1021/jacs.8b07640] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We demonstrate here the rational design of purely entropic domains as a versatile approach to achieve control of the input/output response of synthetic molecular receptors. To do so and to highlight the versatility and generality of this approach, we have rationally re-engineered two model DNA-based receptors: a clamp-like DNA-based switch that recognizes a specific DNA sequence and an ATP-binding aptamer. We show that, by varying the length of the linker domain that connects the two recognition portions of these receptors, it is possible to finely control their affinity for their specific ligand. Through mathematical modeling and thermodynamic characterization, we also demonstrate for both systems that entropy changes associated with changes in linker length are responsible for affinity modulation and that the linker we have designed behaves as a disordered random-coil polymer. The approach also allows us to regulate the ligand concentration range at which the receptors respond and show optimal specificity. Given these attributes, the use of purely entropic domains appears as a versatile and general approach to finely control the activity of synthetic receptors in a highly predictable and controlled fashion.
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Affiliation(s)
- Davide Mariottini
- Chemistry Department , University of Rome Tor Vergata , Via della Ricerca Scientifica , 00133 Rome , Italy
| | - Andrea Idili
- Chemistry Department , University of Rome Tor Vergata , Via della Ricerca Scientifica , 00133 Rome , Italy
| | - Minke A D Nijenhuis
- Institute for Complex Molecular Systems , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
| | - Tom F A de Greef
- Institute for Complex Molecular Systems , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
| | - Francesco Ricci
- Chemistry Department , University of Rome Tor Vergata , Via della Ricerca Scientifica , 00133 Rome , Italy
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