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Sengul MY, MacKerell AD. Influence of Mg 2+ Distribution on the Stability of Folded States of the Twister Ribozyme Revealed Using Grand Canonical Monte Carlo and Generative Deep Learning Enhanced Sampling. ACS OMEGA 2023; 8:19532-19546. [PMID: 37305323 PMCID: PMC10249389 DOI: 10.1021/acsomega.3c00931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 05/11/2023] [Indexed: 06/13/2023]
Abstract
Metal ions, particularly magnesium ions (Mg2+), play a role in stabilizing the tertiary structures of RNA molecules. Theoretical models and experimental techniques show that metal ions can change RNA dynamics and how it transitions through different stages of folding. However, the specific ways in which metal ions contribute to the formation and stabilization of RNA's tertiary structure are not fully understood at the atomic level. Here, we combined oscillating excess chemical potential Grand Canonical Monte Carlo (GCMC) and metadynamics to bias toward the sampling of unfolded states using reaction coordinates generated by machine learning allowing for examination of Mg2+-RNA interactions that contribute to stabilizing folded states of the pseudoknot found in the Twister ribozyme. GCMC is used to sample diverse ion distributions around the RNA with deep learning applied to iteratively generate system-specific reaction coordinates to maximize conformational sampling during metadynamics simulations. Results from 6 μs simulations performed on 9 individual systems indicate that Mg2+ ions play a crucial role in stabilizing the three-dimensional (3D) structure of the RNA by stabilizing specific interactions of phosphate groups or phosphate groups and bases of neighboring nucleotides. While many phosphates are accessible to interactions with Mg2+, it is observed that multiple, specific interactions are required to sample conformations close to the folded state; coordination of Mg2+ at individual specific sites facilitates sampling of folded conformations though unfolding ultimately occurs. It is only when multiple specific interactions occur, including the presence of specific inner-shell cation interactions linking two nucleotides, that conformations close to the folded state are stable. While many of the identified Mg2+ interactions are observed in the X-ray crystal structure of Twister, the present study suggests two new Mg2+ ion sites in the Twister ribozyme that contribute to stabilization. In addition, specific interactions with Mg2+ are observed that destabilize the local RNA structure, a process that may facilitate the folding of RNA into its correct structure.
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2
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Li Y, Arce A, Lucci T, Rasmussen RA, Lucks JB. Dynamic RNA synthetic biology: new principles, practices and potential. RNA Biol 2023; 20:817-829. [PMID: 38044595 PMCID: PMC10730207 DOI: 10.1080/15476286.2023.2269508] [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: 10/28/2023] [Accepted: 08/23/2023] [Indexed: 12/05/2023] Open
Abstract
An increased appreciation of the role of RNA dynamics in governing RNA function is ushering in a new wave of dynamic RNA synthetic biology. Here, we review recent advances in engineering dynamic RNA systems across the molecular, circuit and cellular scales for important societal-scale applications in environmental and human health, and bioproduction. For each scale, we introduce the core concepts of dynamic RNA folding and function at that scale, and then discuss technologies incorporating these concepts, covering new approaches to engineering riboswitches, ribozymes, RNA origami, RNA strand displacement circuits, biomaterials, biomolecular condensates, extracellular vesicles and synthetic cells. Considering the dynamic nature of RNA within the engineering design process promises to spark the next wave of innovation that will expand the scope and impact of RNA biotechnologies.
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Affiliation(s)
- Yueyi Li
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
| | - Anibal Arce
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
| | - Tyler Lucci
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
| | - Rebecca A. Rasmussen
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, USA
| | - Julius B. Lucks
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Graduate Program, Northwestern University, Evanston, IL, USA
- Center for Water Research, Northwestern University, Evanston, IL, USA
- Center for Engineering Sustainability and Resilience, Northwestern University, Evanston, IL, USA
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3
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Spatiotemporally controlled generation of NTPs for single-molecule studies. Nat Chem Biol 2022; 18:1144-1151. [PMID: 36131148 PMCID: PMC9512701 DOI: 10.1038/s41589-022-01100-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 06/29/2022] [Indexed: 12/22/2022]
Abstract
Many essential processes in the cell depend on proteins that use nucleoside triphosphates (NTPs). Methods that directly monitor the often-complex dynamics of these proteins at the single-molecule level have helped to uncover their mechanisms of action. However, the measurement throughput is typically limited for NTP-utilizing reactions, and the quantitative dissection of complex dynamics over multiple sequential turnovers remains challenging. Here we present a method for controlling NTP-driven reactions in single-molecule experiments via the local generation of NTPs (LAGOON) that markedly increases the measurement throughput and enables single-turnover observations. We demonstrate the effectiveness of LAGOON in single-molecule fluorescence and force spectroscopy assays by monitoring DNA unwinding, nucleosome sliding and RNA polymerase elongation. LAGOON can be readily integrated with many single-molecule techniques, and we anticipate that it will facilitate studies of a wide range of crucial NTP-driven processes. ![]()
A new method for controlling NTP-driven reactions in single-molecule experiments via the local generation of NTPs (LAGOON) markedly increases the measurement throughput and enables single-turnover observations.
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4
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Roca J, Santiago-Frangos A, Woodson SA. Diversity of bacterial small RNAs drives competitive strategies for a mutual chaperone. Nat Commun 2022; 13:2449. [PMID: 35508531 PMCID: PMC9068810 DOI: 10.1038/s41467-022-30211-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 04/06/2022] [Indexed: 12/17/2022] Open
Abstract
Hundreds of bacterial small RNAs (sRNAs) require the Hfq chaperone to regulate mRNA expression. Hfq is limiting, thus competition among sRNAs for binding to Hfq shapes the proteomes of individual cells. To understand how sRNAs compete for a common partner, we present a single-molecule fluorescence platform to simultaneously visualize binding and release of multiple sRNAs with Hfq. We show that RNA residents rarely dissociate on their own. Instead, clashes between residents and challengers on the same face of Hfq cause rapid exchange, whereas RNAs that recognize different surfaces may cohabit Hfq for several minutes before one RNA departs. The prevalence of these pathways depends on the structure of each RNA and how it interacts with Hfq. We propose that sRNA diversity creates many pairwise interactions with Hfq that allow for distinct biological outcomes: active exchange favors fast regulation whereas co-residence of dissimilar RNAs favors target co-recognition or target exclusion.
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Affiliation(s)
- Jorjethe Roca
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA
| | - Andrew Santiago-Frangos
- CMDB Program, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA.,Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717, USA
| | - Sarah A Woodson
- T. C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA.
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5
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Tavakoli A, Min JH. Photochemical modifications for DNA/RNA oligonucleotides. RSC Adv 2022; 12:6484-6507. [PMID: 35424630 PMCID: PMC8982246 DOI: 10.1039/d1ra05951c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/27/2021] [Indexed: 11/29/2022] Open
Abstract
Light-triggered chemical reactions can provide excellent tools to investigate the fundamental mechanisms important in biology. Light is easily applicable and orthogonal to most cellular events, and its dose and locality can be controlled in tissues and cells. Light-induced conversion of photochemical groups installed on small molecules, proteins, and oligonucleotides can alter their functional states and thus the ensuing biological events. Recently, photochemical control of DNA/RNA structure and function has garnered attention thanks to the rapidly expanding photochemistry used in diverse biological applications. Photoconvertible groups can be incorporated in the backbone, ribose, and nucleobase of an oligonucleotide to undergo various irreversible and reversible light-induced reactions such as cleavage, crosslinking, isomerization, and intramolecular cyclization reactions. In this review, we gather a list of photoconvertible groups used in oligonucleotides and summarize their reaction characteristics, impacts on DNA/RNA thermal stability and structure, as well as their biological applications.
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Affiliation(s)
- Amirrasoul Tavakoli
- Department of Chemistry & Biochemistry, Baylor University Waco TX 76706 USA +1-254-710-2095
| | - Jung-Hyun Min
- Department of Chemistry & Biochemistry, Baylor University Waco TX 76706 USA +1-254-710-2095
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Kapadia JB, Kharma N, Davis AN, Kamel N, Perreault J. Toehold-mediated strand displacement to measure released product from self-cleaving ribozymes. RNA (NEW YORK, N.Y.) 2022; 28:263-273. [PMID: 34862273 PMCID: PMC8906547 DOI: 10.1261/rna.078823.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 10/27/2021] [Indexed: 06/13/2023]
Abstract
This paper presents a probe comprising a fluorophore and a quencher, enabling measurement of released product from self-cleaving hammerhead ribozyme, without labeled RNA molecules, regular sampling or use of polyacrylamide gels. The probe is made of two DNA strands; one strand is labeled with a fluorophore at its 5'-end, while the other strand is labeled with a quencher at its 3'-end. These two DNA strands are perfectly complementary, but with a 3'-overhang of the fluorophore strand. These unpaired nucleotides act as a toehold, which is utilized by a detached cleaved fragment (coming from a self-cleaving hammerhead ribozyme) as the starting point for a strand displacement reaction. This reaction causes the separation of the fluorophore strand from the quencher strand, culminating in fluorescence, detectable in a plate reader. Notably, the emitted fluorescence is proportional to the amount of detached cleaved-off RNAs, displacing the DNA quencher strand. This method can replace or complement radio-hazardous unstable 32P as a method of measurement of the product release from ribozyme cleavage reactions; it also eliminates the need for polyacrylamide gels, for the same purpose. Critically, this method allows to distinguish between the total amount of cleaved ribozymes and the amount of detached fragments, resulting from that cleavage reaction.
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Affiliation(s)
- Jay Bhakti Kapadia
- Electrical and Computer Engineering Department, Concordia University, Montreal, Quebec, Canada H3G 1M8
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec, Canada H7V 1B7
| | - Nawwaf Kharma
- Electrical and Computer Engineering Department, Concordia University, Montreal, Quebec, Canada H3G 1M8
- Centre for Applied Synthetic Biology (CASB), Concordia University, Montreal, Quebec, Canada H4B 1R6
| | - Alen Nellikulam Davis
- Electrical and Computer Engineering Department, Concordia University, Montreal, Quebec, Canada H3G 1M8
| | - Nicolas Kamel
- Electrical and Computer Engineering Department, Concordia University, Montreal, Quebec, Canada H3G 1M8
| | - Jonathan Perreault
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, Quebec, Canada H7V 1B7
- Centre for Applied Synthetic Biology (CASB), Concordia University, Montreal, Quebec, Canada H4B 1R6
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7
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Ma Y, Mou Q, Yan P, Yang Z, Xiong Y, Yan D, Zhang C, Zhu X, Lu Y. A highly sensitive and selective fluoride sensor based on a riboswitch-regulated transcription coupled with CRISPR-Cas13a tandem reaction. Chem Sci 2021; 12:11740-11747. [PMID: 34659710 PMCID: PMC8442723 DOI: 10.1039/d1sc03508h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 07/20/2021] [Indexed: 12/26/2022] Open
Abstract
Nucleic acid sensors have realized much success in detecting positively charged and neutral molecules, but have rarely been applied for measuring negatively charged molecules, such as fluoride, even though an effective sensor is needed to promote dental health while preventing osteofluorosis and other diseases. To address this issue, we herein report a quantitative fluoride sensor with a portable fluorometer readout based on fluoride riboswitch-regulated transcription coupled with CRISPR-Cas13-based signal amplification. This tandem sensor utilizes the fluoride riboswitch to regulate in vitro transcription and generate full-length transcribed RNA that can be recognized by CRISPR-Cas13a, triggering the collateral cleavage of the fluorophore-quencher labeled RNA probe and generating a fluorescence signal output. This tandem sensor can quantitatively detect fluoride at ambient temperature in aqueous solution with high sensitivity (limit of detection (LOD) ≈ 1.7 μM), high selectivity against other common anions, a wide dynamic range (0-800 μM) and a short sample-to-answer time (30 min). This work expands the application of nucleic acid sensors to negatively charged targets and demonstrates their potential for the on-site and real-time detection of fluoride in environmental monitoring and point-of-care diagnostics.
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Affiliation(s)
- Yuan Ma
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China
| | - Quanbing Mou
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Peng Yan
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University 710049 Xi'an PR China
| | - Zhenglin Yang
- Department of Biochemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Ying Xiong
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Deyue Yan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China
| | - Chuan Zhang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China
| | - Xinyuan Zhu
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
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8
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Yang L, Trentini D, Kim H, Sul J, Eberwine JH, Dmochowski IJ. Photoactivatable Circular Caged Oligonucleotides for Transcriptome In Vivo Analysis (TIVA). CHEMPHOTOCHEM 2021; 5:940-946. [DOI: 10.1002/cptc.202100098] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Linlin Yang
- Department of Chemistry University of Pennsylvania 231 South 34th Street Philadelphia PA 19104-6323 USA
| | - Dora Trentini
- Department of Chemistry University of Pennsylvania 231 South 34th Street Philadelphia PA 19104-6323 USA
| | - HyunBum Kim
- Department of Pharmacology University of Pennsylvania 38 John Morgan Building 3620 Hamilton Walk Philadelphia PA 19104-6084 USA
| | - Jai‐Yoon Sul
- Department of Pharmacology University of Pennsylvania 38 John Morgan Building 3620 Hamilton Walk Philadelphia PA 19104-6084 USA
| | - James H. Eberwine
- Department of Pharmacology University of Pennsylvania 38 John Morgan Building 3620 Hamilton Walk Philadelphia PA 19104-6084 USA
| | - Ivan J. Dmochowski
- Department of Chemistry University of Pennsylvania 231 South 34th Street Philadelphia PA 19104-6323 USA
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9
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Akhmetova EA, Golyshev VM, Vokhtantcev IP, Meschaninova MI, Venyaminova AG, Novopashina DS. Photoactivatable CRISPR/Cas9 System. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2021. [DOI: 10.1134/s1068162021020023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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10
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Yang L, Dmochowski IJ. Conditionally Activated ("Caged") Oligonucleotides. Molecules 2021; 26:1481. [PMID: 33803234 PMCID: PMC7963183 DOI: 10.3390/molecules26051481] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 01/09/2023] Open
Abstract
Conditionally activated ("caged") oligonucleotides provide useful spatiotemporal control for studying dynamic biological processes, e.g., regulating in vivo gene expression or probing specific oligonucleotide targets. This review summarizes recent advances in caging strategies, which involve different stimuli in the activation step. Oligo cyclization is a particularly attractive caging strategy, which simplifies the probe design and affords oligo stabilization. Our laboratory developed an efficient synthesis for circular caged oligos, and a circular caged antisense DNA oligo was successfully applied in gene regulation. A second technology is Transcriptome In Vivo Analysis (TIVA), where caged oligos enable mRNA isolation from single cells in living tissue. We highlight our development of TIVA probes with improved caging stability. Finally, we illustrate the first protease-activated oligo probe, which was designed for caspase-3. This expands the toolkit for investigating the transcriptome under a specific physiologic condition (e.g., apoptosis), particularly in specimens where light activation is impractical.
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Affiliation(s)
| | - Ivan J. Dmochowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA;
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11
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Weinstain R, Slanina T, Kand D, Klán P. Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials. Chem Rev 2020; 120:13135-13272. [PMID: 33125209 PMCID: PMC7833475 DOI: 10.1021/acs.chemrev.0c00663] [Citation(s) in RCA: 256] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 02/08/2023]
Abstract
Photoactivatable (alternatively, photoremovable, photoreleasable, or photocleavable) protecting groups (PPGs), also known as caged or photocaged compounds, are used to enable non-invasive spatiotemporal photochemical control over the release of species of interest. Recent years have seen the development of PPGs activatable by biologically and chemically benign visible and near-infrared (NIR) light. These long-wavelength-absorbing moieties expand the applicability of this powerful method and its accessibility to non-specialist users. This review comprehensively covers organic and transition metal-containing photoactivatable compounds (complexes) that absorb in the visible- and NIR-range to release various leaving groups and gasotransmitters (carbon monoxide, nitric oxide, and hydrogen sulfide). The text also covers visible- and NIR-light-induced photosensitized release using molecular sensitizers, quantum dots, and upconversion and second-harmonic nanoparticles, as well as release via photodynamic (photooxygenation by singlet oxygen) and photothermal effects. Release from photoactivatable polymers, micelles, vesicles, and photoswitches, along with the related emerging field of photopharmacology, is discussed at the end of the review.
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Affiliation(s)
- Roy Weinstain
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Tomáš Slanina
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague, Czech Republic
| | - Dnyaneshwar Kand
- School
of Plant Sciences and Food Security, Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 6997801, Israel
| | - Petr Klán
- Department
of Chemistry and RECETOX, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
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12
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Kognole AA, MacKerell AD. Contributions and competition of Mg 2+ and K + in folding and stabilization of the Twister ribozyme. RNA (NEW YORK, N.Y.) 2020; 26:1704-1715. [PMID: 32769092 PMCID: PMC7566569 DOI: 10.1261/rna.076851.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
Native folded and compact intermediate states of RNA typically involve tertiary structures in the presence of divalent ions such as Mg2+ in a background of monovalent ions. In a recent study, we have shown how the presence of Mg2+ impacts the transition from partially unfolded to folded states through a "push-pull" mechanism where the ion both favors and disfavors the sampling of specific phosphate-phosphate interactions. To further understand the ion atmosphere of RNA in folded and partially folded states results from atomistic umbrella sampling and oscillating chemical potential grand canonical Monte Carlo/molecular dynamics (GCMC/MD) simulations are used to obtain atomic-level details of the distributions of Mg2+ and K+ ions around Twister RNA. Results show the presence of 100 mM Mg2+ to lead to increased charge neutralization over that predicted by counterion condensation theory. Upon going from partially unfolded to folded states, overall charge neutralization increases at all studied ion concentrations that, while associated with an increase in the number of direct ion-phosphate interactions, is fully accounted for by the monovalent K+ ions. Furthermore, K+ preferentially interacts with purine N7 atoms of helical regions in partially unfolded states, thereby potentially stabilizing the helical regions. Thus, both secondary helical structures and formation of tertiary structures leads to increased counterion condensation, thereby stabilizing those structural features of Twister. Notably, it is shown that K+ can act as a surrogate for Mg2+ by participating in specific interactions with nonsequential phosphate pairs that occur in the folded state, explaining the ability of Twister to self-cleave at submillimolar Mg2+ concentrations.
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Affiliation(s)
- Abhishek A Kognole
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA
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