1
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Khandave NP, Hansen DF, Vallurupalli P. Increasing the accuracy of exchange parameters reporting on slow dynamics by performing CEST experiments with 'high' B 1 fields. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 363:107699. [PMID: 38851059 DOI: 10.1016/j.jmr.2024.107699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/11/2024] [Accepted: 05/11/2024] [Indexed: 06/10/2024]
Abstract
Over the last decade chemical exchange saturation transfer (CEST) NMR methods have emerged as powerful tools to characterize biomolecular conformational dynamics occurring between a visible major state and 'invisible' minor states. The ability of the CEST experiment to detect these minor states, and provide precise exchange parameters, hinges on using appropriate B1 field strengths during the saturation period. Typically, a pair of B1 fields with ω1 (=2πB1) values around the exchange rate kex are chosen. Here we show that the transverse relaxation rate of the minor state resonance (R2,B) also plays a crucial role in determining the B1 fields that lead to the most informative datasets. Using [Formula: see text] ≥ kex, to guide the choice of B1, instead of kex, leads to data wherefrom substantially more accurate exchange parameters can be derived. The need for higher B1 fields, guided by K, is demonstrated by studying the conformational exchange in two mutants of the 71 residue FF domain with kex ∼ 11 s-1 and ∼ 72 s-1, respectively. In both cases analysis of CEST datasets recorded using B1 field values guided by kex lead to imprecise exchange parameters, whereas using B1 values guided by K resulted in precise site-specific exchange parameters. The conclusions presented here will be valuable while using CEST to study slow processes at sites with large intrinsic relaxation rates, including carbonyl sites in small to medium sized proteins, amide 15N sites in large proteins and when the minor state dips are broadened due to exchange among the minor states.
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Affiliation(s)
- Nihar Pradeep Khandave
- Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500046, India
| | - D Flemming Hansen
- Department of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom; The Francis Crick Institute, London, NW1 1BF, United Kingdom.
| | - Pramodh Vallurupalli
- Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500046, India.
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2
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Varghese CN, Jaladeep A, Sekhar A. Measuring Hydroxyl Exchange Rates in Glycans Using a Synergistic Combination of Saturation Transfer and Relaxation Dispersion NMR. J Am Chem Soc 2024; 146:3825-3835. [PMID: 38293947 PMCID: PMC7615893 DOI: 10.1021/jacs.3c10982] [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: 02/01/2024]
Abstract
Molecular recognition events mediated by glycans play pivotal roles in controlling the fate of diverse biological processes such as cellular communication and the immune response. The affinity of glycans for their target receptors is governed primarily by the hydrogen bonds formed by hydroxyl groups decorating the glycan surface. Hydroxyl exchange rate constants are therefore vital parameters that report on glycan structure and dynamics. Here we present a strategy for characterizing hydroxyl hydrogen/deuterium (H/D) exchange in glycans that employs a synergistic combination of 13C chemical exchange saturation transfer (CEST) and Carr-Purcell-Meiboom-Gill relaxation dispersion (CPMG) NMR methods. We show that the combination of CEST and CPMG experiments facilitates the sensitive detection of the small (∼0.1 ppm) two-bond deuterium isotope shift on a 13C nucleus when the attached hydroxyl group fluctuates between protonated and deuterated states. This shift is leveraged for measuring site-specific kinetic H/D exchange rate constants as well as thermodynamic free energies of isotope fractionation. The CEST and CPMG modules are integrated with a selective J-cross-polarization scheme that provides the flexibility for rapid characterization of H/D exchange at a specific hydroxyl site. Moreover, our approach enables the precise isothermal measurement of hydroxyl exchange rate constants without the need for cumbersome isotope labeling. The H/D exchange rate constants of three different glycans assessed using this method highlight its potential for detecting transient intra- and intermolecular hydrogen bonds. In addition, the trends in H/D exchange rate constants establish site-specific steric accessibility as a key determinant of solvent exchange dynamics in glycans.
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Affiliation(s)
- Claris Niya Varghese
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India
| | - Ahallya Jaladeep
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India
| | - Ashok Sekhar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India
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3
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Lu J, Straub JS, Nowotarski MS, Han S, Xu X, Jerschow A. Spectroscopically dark phosphate features revealed by chemical exchange saturation transfer. NMR IN BIOMEDICINE 2024; 37:e5057. [PMID: 37853675 DOI: 10.1002/nbm.5057] [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: 05/20/2023] [Revised: 08/16/2023] [Accepted: 09/13/2023] [Indexed: 10/20/2023]
Abstract
Phosphate is an essential anion in the human body, comprising approximately 1% of the total body weight, and playing a vital role in metabolism, cell membranes, and bone formation. We have recently provided spectroscopic, microscopic, and computational evidence indicating that phosphates can aggregate much more readily in solution than previously thought. This prior work provided indirect evidence through the observation of unusual31 P NMR relaxation and line-broadening effects with increasing temperature. Here, we show that, under conditions of slow exchange and selective RF saturation, additional features become visible in chemical exchange saturation transfer (CEST) experiments, which appear to be related to the previously reported phosphate clustering. In particular, CEST shows pronounced dips several ppm upfield of the main phosphate resonance at low temperatures, while direct31 P spectroscopy does not produce any signals in that range. We study the pH dependence of these new spectroscopic features and present exchange and spectroscopic parameters based on fitting the CEST data. These findings could be of importance in the investigation of phosphate dynamics, especially in the biological milieu.
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Affiliation(s)
- Jiaqi Lu
- Department of Chemistry, New York University, New York, USA
| | - Joshua S Straub
- Department of Physics, University of California, Santa Barbara, California, USA
| | | | - Songi Han
- Department of Chemistry, University of California, Santa Barbara, California, USA
- Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Xiang Xu
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, USA
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4
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Gu S, Szymanski ES, Rangadurai AK, Shi H, Liu B, Manghrani A, Al-Hashimi HM. Dynamic basis for dA•dGTP and dA•d8OGTP misincorporation via Hoogsteen base pairs. Nat Chem Biol 2023; 19:900-910. [PMID: 37095237 DOI: 10.1038/s41589-023-01306-5] [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: 08/19/2022] [Accepted: 03/08/2023] [Indexed: 04/26/2023]
Abstract
Replicative errors contribute to the genetic diversity needed for evolution but in high frequency can lead to genomic instability. Here, we show that DNA dynamics determine the frequency of misincorporating the A•G mismatch, and altered dynamics explain the high frequency of 8-oxoguanine (8OG) A•8OG misincorporation. NMR measurements revealed that Aanti•Ganti (population (pop.) of >91%) transiently forms sparsely populated and short-lived Aanti+•Gsyn (pop. of ~2% and kex = kforward + kreverse of ~137 s-1) and Asyn•Ganti (pop. of ~6% and kex of ~2,200 s-1) Hoogsteen conformations. 8OG redistributed the ensemble, rendering Aanti•8OGsyn the dominant state. A kinetic model in which Aanti+•Gsyn is misincorporated quantitatively predicted the dA•dGTP misincorporation kinetics by human polymerase β, the pH dependence of misincorporation and the impact of the 8OG lesion. Thus, 8OG increases replicative errors relative to G because oxidation of guanine redistributes the ensemble in favor of the mutagenic Aanti•8OGsyn Hoogsteen state, which exists transiently and in low abundance in the A•G mismatch.
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Affiliation(s)
- Stephanie Gu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Eric S Szymanski
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Base4, Durham, NC, USA
| | - Atul K Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Hospital for Sick Children, Toronto, Ontario, Canada
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, USA
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Akanksha Manghrani
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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5
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Overbeck JH, Vögele J, Nussbaumer F, Duchardt‐Ferner E, Kreutz C, Wöhnert J, Sprangers R. 19F NMR Untersuchung des Konformationsaustauschs mehrerer Zustände im synthetischen Neomycin-bindenden Riboschalter. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 135:e202218064. [PMID: 38516132 PMCID: PMC10953372 DOI: 10.1002/ange.202218064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Indexed: 03/29/2023]
Abstract
AbstractDer synthetische Neomycin‐bindende Riboschalter interagiert mit seinem Liganden Neomycin sowie mit den verwandten Antibiotika Ribostamycin und Paromomycin. Die Bindung dieser Aminoglykoside induziert sehr ähnliche Grundzustandsstrukturen in der RNA, allerdings kann nur Neomycin die Initiierung der Translation effizient unterdrücken. Der molekulare Ursprung dieser Unterschiede wurde auf Unterschiede in der Dynamik der Ligand‐Riboschalter‐Komplexe zurückgeführt. In diesem Artikel kombinieren wir fünf komplementäre fluorbasierte NMR‐Methoden, um die Dynamik der drei Riboschalter‐Komplexe im Sekunden‐ bis Mikrosekundenbereich genau zu quantifizieren. Unsere Daten offenbaren komplexe Austauschprozesse mit bis zu vier strukturell unterschiedlichen Zuständen. Wir interpretieren unsere Ergebnisse in einem Modell, das ein Zusammenspiel zwischen verschiedenen chemischen Gruppen in den Antibiotika und spezifischen Basen im Riboschalter zeigt. Allgemeiner unterstreichen unsere Daten das Potenzial von 19F NMR‐Methoden, komplexe Austauschprozesse mit mehreren angeregten Zuständen zu charakterisieren.
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Affiliation(s)
- Jan H. Overbeck
- Department of Biophysics IRegensburg Center for BiochemistryUniversity of RegensburgUniversitätsstrasse 3193051RegensburgDeutschland
| | - Jennifer Vögele
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Deutschland
| | - Felix Nussbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnsbruckÖsterreich
| | - Elke Duchardt‐Ferner
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Deutschland
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnsbruckÖsterreich
| | - Jens Wöhnert
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Deutschland
| | - Remco Sprangers
- Department of Biophysics IRegensburg Center for BiochemistryUniversity of RegensburgUniversitätsstrasse 3193051RegensburgDeutschland
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6
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Overbeck JH, Vögele J, Nussbaumer F, Duchardt‐Ferner E, Kreutz C, Wöhnert J, Sprangers R. Multi-Site Conformational Exchange in the Synthetic Neomycin-Sensing Riboswitch Studied by 19 F NMR. Angew Chem Int Ed Engl 2023; 62:e202218064. [PMID: 36970768 PMCID: PMC10952710 DOI: 10.1002/anie.202218064] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/24/2023] [Accepted: 03/22/2023] [Indexed: 03/28/2023]
Abstract
The synthetic neomycin-sensing riboswitch interacts with its cognate ligand neomycin as well as with the related antibiotics ribostamycin and paromomycin. Binding of these aminoglycosides induces a very similar ground state structure in the RNA, however, only neomycin can efficiently repress translation initiation. The molecular origin of these differences has been traced back to differences in the dynamics of the ligand:riboswitch complexes. Here, we combine five complementary fluorine based NMR methods to accurately quantify seconds to microseconds dynamics in the three riboswitch complexes. Our data reveal complex exchange processes with up to four structurally different states. We interpret our findings in a model that shows an interplay between different chemical groups in the antibiotics and specific bases in the riboswitch. More generally, our data underscore the potential of 19 F NMR methods to characterize complex exchange processes with multiple excited states.
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Affiliation(s)
- Jan H. Overbeck
- Department of Biophysics IRegensburg Center for BiochemistryUniversity of RegensburgUniversitätsstrasse 3193051RegensburgGermany
| | - Jennifer Vögele
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Germany
| | - Felix Nussbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnsbruckAustria
| | - Elke Duchardt‐Ferner
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Germany
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnsbruckAustria
| | - Jens Wöhnert
- Institute for Molecular BiosciencesGoethe-University FrankfurtMax-von-Laue-Str. 960438Frankfurt/M.Germany
| | - Remco Sprangers
- Department of Biophysics IRegensburg Center for BiochemistryUniversity of RegensburgUniversitätsstrasse 3193051RegensburgGermany
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7
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Taiwo KM, Nam H, LeBlanc RM, Longhini AP, Dayie TK. Cross-correlated relaxation rates provide facile exchange signature in selectively labeled RNA. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 342:107245. [PMID: 35908529 DOI: 10.1016/j.jmr.2022.107245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
Gerhard Wagner has made numerous contributions to NMR spectroscopy, particularly his developments in the field of spin-relaxation stand out in directly mapping the spectral density functions of proteins. He and his group developed experimental techniques to reveal the importance of dynamics to protein biological function and drug discovery. On his 75th birthday, we take this opportunity to highlight how some of those seminal ideas developed for proteins are being extended to RNAs. The role of dynamics in the structure and function of RNA has been a major interest in drug design and therapeutics. Here we present the use of cross-correlated relaxation rates (ηxy) from anti-TROSY (R2α) and TROSY (R2β) to rapidly obtain qualitative information about the chemical exchange taking place within the bacterial and human A-site RNA system while reducing the sets of relaxation experiments required to map dynamics. We show that ηxy correlates with the order parameter which gives information on how flexible or rigid a residue is. We further show R2β/ηxy can rapidly be used to probe chemical exchange as seen from its agreement with Rex. In addition, we report the ability of R2β/ηxy to determine chemical exchange taking place within the bacterial A-site RNA during structural transitions at pH 6.2 and 6.5. Finally, comparison of the R2β/ηxy ratios indicates bacterial A-site has greater R2β/ηxy values for G19 (1.34 s-1), A20 (1.38 s-1), U23 (1.63 s-1) and C24 (1.51 s-1) than human A-site [A19 (0.76 s-1), A20 (1.01 s-1), U23 (0.74 s-1) and C24 (0.71 s-1)]. Taken together, we have shown that the chemical exchange can quickly be analyzed for RNA systems from cross-correlated relaxation rates.
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Affiliation(s)
- Kehinde M Taiwo
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States.
| | - Hyeyeon Nam
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States
| | - Regan M LeBlanc
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States
| | - Andrew P Longhini
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States
| | - Theodore K Dayie
- Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, United States.
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8
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Dayie TK, Olenginski LT, Taiwo KM. Isotope Labels Combined with Solution NMR Spectroscopy Make Visible the Invisible Conformations of Small-to-Large RNAs. Chem Rev 2022; 122:9357-9394. [PMID: 35442658 PMCID: PMC9136934 DOI: 10.1021/acs.chemrev.1c00845] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Indexed: 02/07/2023]
Abstract
RNA is central to the proper function of cellular processes important for life on earth and implicated in various medical dysfunctions. Yet, RNA structural biology lags significantly behind that of proteins, limiting mechanistic understanding of RNA chemical biology. Fortunately, solution NMR spectroscopy can probe the structural dynamics of RNA in solution at atomic resolution, opening the door to their functional understanding. However, NMR analysis of RNA, with only four unique ribonucleotide building blocks, suffers from spectral crowding and broad linewidths, especially as RNAs grow in size. One effective strategy to overcome these challenges is to introduce NMR-active stable isotopes into RNA. However, traditional uniform labeling methods introduce scalar and dipolar couplings that complicate the implementation and analysis of NMR measurements. This challenge can be circumvented with selective isotope labeling. In this review, we outline the development of labeling technologies and their application to study biologically relevant RNAs and their complexes ranging in size from 5 to 300 kDa by NMR spectroscopy.
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Affiliation(s)
- Theodore K. Dayie
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Lukasz T. Olenginski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Kehinde M. Taiwo
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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9
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Zhou Y, Jiang Y, Chen SJ. RNA-ligand molecular docking: advances and challenges. WILEY INTERDISCIPLINARY REVIEWS. COMPUTATIONAL MOLECULAR SCIENCE 2022; 12:e1571. [PMID: 37293430 PMCID: PMC10250017 DOI: 10.1002/wcms.1571] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/20/2021] [Indexed: 12/16/2022]
Abstract
With rapid advances in computer algorithms and hardware, fast and accurate virtual screening has led to a drastic acceleration in selecting potent small molecules as drug candidates. Computational modeling of RNA-small molecule interactions has become an indispensable tool for RNA-targeted drug discovery. The current models for RNA-ligand binding have mainly focused on the docking-and-scoring method. Accurate docking and scoring should tackle four crucial problems: (1) conformational flexibility of ligand, (2) conformational flexibility of RNA, (3) efficient sampling of binding sites and binding poses, and (4) accurate scoring of different binding modes. Moreover, compared with the problem of protein-ligand docking, predicting ligand binding to RNA, a negatively charged polymer, is further complicated by additional effects such as metal ion effects. Thermodynamic models based on physics-based and knowledge-based scoring functions have shown highly encouraging success in predicting ligand binding poses and binding affinities. Recently, kinetic models for ligand binding have further suggested that including dissociation kinetics (residence time) in ligand docking would result in improved performance in estimating in vivo drug efficacy. More recently, the rise of deep-learning approaches has led to new tools for predicting RNA-small molecule binding. In this review, we present an overview of the recently developed computational methods for RNA-ligand docking and their advantages and disadvantages.
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Affiliation(s)
- Yuanzhe Zhou
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
| | - Yangwei Jiang
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
| | - Shi-Jie Chen
- Department of Physics and Astronomy, Department of Biochemistry, Institute of Data Sciences and Informatics, University of Missouri, Columbia, MO 65211-7010, USA
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10
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Jaroszewicz M, Altenhof AR, Schurko RW, Frydman L. Sensitivity Enhancement by Progressive Saturation of the Proton Reservoir: A Solid-State NMR Analogue of Chemical Exchange Saturation Transfer. J Am Chem Soc 2021; 143:19778-19784. [PMID: 34793152 PMCID: PMC8640991 DOI: 10.1021/jacs.1c08277] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Indexed: 01/10/2023]
Abstract
Chemical exchange saturation transfer (CEST) enhances solution-state NMR signals of labile and otherwise invisible chemical sites, by indirectly detecting their signatures as a highly magnified saturation of an abundant resonance─for instance, the 1H resonance of water. Stimulated by this sensitivity magnification, this study presents PROgressive Saturation of the Proton Reservoir (PROSPR), a method for enhancing the NMR sensitivity of dilute heteronuclei in static solids. PROSPR aims at using these heteronuclei to progressively deplete the abundant 1H polarization found in most organic and several inorganic solids, and implements this 1H signal depletion in a manner that reflects the spectral intensities of the heteronuclei as a function of their chemical shifts or quadrupolar offsets. To achieve this, PROSPR uses a looped cross-polarization scheme that repeatedly depletes 1H-1H local dipolar order and then relays this saturation throughout the full 1H reservoir via spin-diffusion processes that act as analogues of chemical exchanges in the CEST experiment. Repeating this cross-polarization/spin-diffusion procedure multiple times results in an effective magnification of each heteronucleus's response that, when repeated in a frequency-stepped fashion, indirectly maps their NMR spectrum as sizable attenuations of the abundant 1H NMR signal. Experimental PROSPR examples demonstrate that, in this fashion, faithful wideline NMR spectra can be obtained. These 1H-detected heteronuclear NMR spectra can have their sensitivity enhanced by orders of magnitude in comparison to optimized direct-detect experiments targeting unreceptive nuclei at low natural abundance, using modest hardware requirements and conventional NMR equipment at room temperature.
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Affiliation(s)
- Michael
J. Jaroszewicz
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 7610001, Israel
| | - Adam R. Altenhof
- Department
of Chemistry and Biochemistry, Florida State
University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Robert W. Schurko
- Department
of Chemistry and Biochemistry, Florida State
University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Lucio Frydman
- Department
of Chemical and Biological Physics, Weizmann
Institute of Science, Rehovot 7610001, Israel
- National
High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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11
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Liu B, Rangadurai A, Shi H, Al-Hashimi H. Rapid assessment of Watson-Crick to Hoogsteen exchange in unlabeled DNA duplexes using high-power SELOPE imino 1H CEST. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:715-731. [PMID: 37905209 PMCID: PMC10539785 DOI: 10.5194/mr-2-715-2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 09/05/2021] [Indexed: 11/01/2023]
Abstract
In duplex DNA, Watson-Crick A-T and G-C base pairs (bp's) exist in dynamic equilibrium with an alternative Hoogsteen conformation, which is low in abundance and short-lived. Measuring how the Hoogsteen dynamics varies across different DNA sequences, structural contexts and physiological conditions is key for identifying potential Hoogsteen hot spots and for understanding the potential roles of Hoogsteen base pairs in DNA recognition and repair. However, such studies are hampered by the need to prepare 13 C or 15 N isotopically enriched DNA samples for NMR relaxation dispersion (RD) experiments. Here, using SELective Optimized Proton Experiments (SELOPE) 1 H CEST experiments employing high-power radiofrequency fields (B 1 > 250 Hz) targeting imino protons, we demonstrate accurate and robust characterization of Watson-Crick to Hoogsteen exchange, without the need for isotopic enrichment of the DNA. For 13 residues in three DNA duplexes under different temperature and pH conditions, the exchange parameters deduced from high-power imino 1 H CEST were in very good agreement with counterparts measured using off-resonance 13 C / 15 N spin relaxation in the rotating frame (R 1 ρ ). It is shown that 1 H-1 H NOE effects which typically introduce artifacts in 1 H-based measurements of chemical exchange can be effectively suppressed by selective excitation, provided that the relaxation delay is short (≤ 100 ms). The 1 H CEST experiment can be performed with ∼ 10× higher throughput and ∼ 100× lower cost relative to 13 C / 15 N R 1 ρ and enabled Hoogsteen chemical exchange measurements undetectable by R 1 ρ . The results reveal an increased propensity to form Hoogsteen bp's near terminal ends and a diminished propensity within A-tract motifs. The 1 H CEST experiment provides a basis for rapidly screening Hoogsteen breathing in duplex DNA, enabling identification of unusual motifs for more in-depth characterization.
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Affiliation(s)
- Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Department of Chemistry, Duke University, Durham, NC, USA
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12
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Liu B, Shi H, Rangadurai A, Nussbaumer F, Chu CC, Erharter KA, Case DA, Kreutz C, Al-Hashimi HM. A quantitative model predicts how m 6A reshapes the kinetic landscape of nucleic acid hybridization and conformational transitions. Nat Commun 2021; 12:5201. [PMID: 34465779 PMCID: PMC8408185 DOI: 10.1038/s41467-021-25253-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 07/21/2021] [Indexed: 11/18/2022] Open
Abstract
N6-methyladenosine (m6A) is a post-transcriptional modification that controls gene expression by recruiting proteins to RNA sites. The modification also slows biochemical processes through mechanisms that are not understood. Using temperature-dependent (20°C-65°C) NMR relaxation dispersion, we show that m6A pairs with uridine with the methylamino group in the anti conformation to form a Watson-Crick base pair that transiently exchanges on the millisecond timescale with a singly hydrogen-bonded low-populated (1%) mismatch-like conformation in which the methylamino group is syn. This ability to rapidly interchange between Watson-Crick or mismatch-like forms, combined with different syn:anti isomer preferences when paired (~1:100) versus unpaired (~10:1), explains how m6A robustly slows duplex annealing without affecting melting at elevated temperatures via two pathways in which isomerization occurs before or after duplex annealing. Our model quantitatively predicts how m6A reshapes the kinetic landscape of nucleic acid hybridization and conformational transitions, and provides an explanation for why the modification robustly slows diverse cellular processes.
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Affiliation(s)
- Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Felix Nussbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Chia-Chieh Chu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Kevin Andreas Erharter
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - David A Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
- Department of Chemistry, Duke University, Durham, NC, USA.
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13
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Hoogstraten CG, Terrazas M, Aviñó A, White NA, Sumita M. Dynamics-Function Analysis in Catalytic RNA Using NMR Spin Relaxation and Conformationally Restricted Nucleotides. Methods Mol Biol 2021; 2167:183-202. [PMID: 32712921 DOI: 10.1007/978-1-0716-0716-9_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A full understanding of biomolecular function requires an analysis of both the dynamic properties of the system of interest and the identification of those dynamics that are required for function. We describe NMR methods based on metabolically directed specific isotope labeling for the identification of molecular disorder and/or conformational transitions on the RNA backbone ribose groups. These analyses are complemented by the use of synthetic covalently modified nucleotides constrained to a single sugar pucker, which allow functional assessment of dynamics by selectively removing a minor conformer identified by NMR from the structural ensemble.
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Affiliation(s)
- Charles G Hoogstraten
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.
| | - Montserrat Terrazas
- Institute for Advanced Chemistry of Catalonia (IQAC), Spanish Council for Scientific Research (CSIC), Barcelona, Spain.,Joint IRB-BSC Program in Computational Biology, The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC), Spanish Council for Scientific Research (CSIC), Barcelona, Spain.,Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Neil A White
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.,Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA
| | - Minako Sumita
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.,Department of Chemistry, Southern Illinois University Edwardsville, Edwardsville, IL, USA
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14
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Base-Pair Opening Dynamics Study of Fluoride Riboswitch in the Bacillus cereus CrcB Gene. Int J Mol Sci 2021; 22:ijms22063234. [PMID: 33810132 PMCID: PMC8004769 DOI: 10.3390/ijms22063234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 11/16/2022] Open
Abstract
Riboswitches are segments of noncoding RNA that bind with metabolites, resulting in a change in gene expression. To understand the molecular mechanism of gene regulation in a fluoride riboswitch, a base-pair opening dynamics study was performed with and without ligands using the Bacillus cereus fluoride riboswitch. We demonstrate that the structural stability of the fluoride riboswitch is caused by two steps depending on ligands. Upon binding of a magnesium ion, significant changes in a conformation of the riboswitch occur, resulting in the greatest increase in their stability and changes in dynamics by a fluoride ion. Examining hydrogen exchange dynamics through NMR spectroscopy, we reveal that the stabilization of the U45·A37 base-pair due to the binding of the fluoride ion, by changing the dynamics while maintaining the structure, results in transcription regulation. Our results demonstrate that the opening dynamics and stabilities of a fluoride riboswitch in different ion states are essential for the genetic switching mechanism.
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15
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Beckwith MA, Erazo-Colon T, Johnson BA. RING NMR dynamics: software for analysis of multiple NMR relaxation experiments. JOURNAL OF BIOMOLECULAR NMR 2021; 75:9-23. [PMID: 33098475 PMCID: PMC7897199 DOI: 10.1007/s10858-020-00350-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/23/2020] [Indexed: 05/05/2023]
Abstract
Molecular motions are fundamental to the existence of life, and NMR spectroscopy remains one of the most useful and powerful methods to measure their rates and molecular characteristics. Multiple experimental methods are available for measuring the NMR relaxation properties and these can require different methods for extracting model parameters. We present here a new software application, RING NMR Dynamics, that is designed to support analysis of multiple relaxation types. The initial release of RING NMR Dynamics supports the analysis of exponential decay experiments such as T1 and T2, as well as CEST and R2 and R1ρ relaxation dispersion. The software runs on multiple operating systems in both a command line mode and a user-friendly GUI that allows visualizing and simulating relaxation data. Interaction with another program, NMRFx Analyst, allows drilling down from the derived relaxation parameters to the raw spectral data.
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Affiliation(s)
- Martha A Beckwith
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Teddy Erazo-Colon
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Bruce A Johnson
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, NY, 10031, USA.
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16
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Abou Assi H, Rangadurai AK, Shi H, Liu B, Clay MC, Erharter K, Kreutz C, Holley CL, Al-Hashimi H. 2'-O-Methylation can increase the abundance and lifetime of alternative RNA conformational states. Nucleic Acids Res 2020; 48:12365-12379. [PMID: 33104789 PMCID: PMC7708057 DOI: 10.1093/nar/gkaa928] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/10/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
2'-O-Methyl (Nm) is a highly abundant post-transcriptional RNA modification that plays important biological roles through mechanisms that are not entirely understood. There is evidence that Nm can alter the biological activities of RNAs by biasing the ribose sugar pucker equilibrium toward the C3'-endo conformation formed in canonical duplexes. However, little is known about how Nm might more broadly alter the dynamic ensembles of flexible RNAs containing bulges and internal loops. Here, using NMR and the HIV-1 transactivation response (TAR) element as a model system, we show that Nm preferentially stabilizes alternative secondary structures in which the Nm-modified nucleotides are paired, increasing both the abundance and lifetime of low-populated short-lived excited states by up to 10-fold. The extent of stabilization increased with number of Nm modifications and was also dependent on Mg2+. Through phi-value analysis, the Nm modification also provided rare insights into the structure of the transition state for conformational exchange. Our results suggest that Nm could alter the biological activities of Nm-modified RNAs by modulating their secondary structural ensembles as well as establish the utility of Nm as a tool for the discovery and characterization of RNA excited state conformations.
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Affiliation(s)
- Hala Abou Assi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Atul K Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | - Bei Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mary C Clay
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kevin Erharter
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, 6020 Innsbruck, Austria
| | - Christopher L Holley
- Department of Medicine, Duke University School of Medicine, Durham, NC 27710, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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17
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Overbeck JH, Kremer W, Sprangers R. A suite of 19F based relaxation dispersion experiments to assess biomolecular motions. JOURNAL OF BIOMOLECULAR NMR 2020; 74:753-766. [PMID: 32997265 PMCID: PMC7701166 DOI: 10.1007/s10858-020-00348-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/18/2020] [Indexed: 05/08/2023]
Abstract
Proteins and nucleic acids are highly dynamic bio-molecules that can populate a variety of conformational states. NMR relaxation dispersion (RD) methods are uniquely suited to quantify the associated kinetic and thermodynamic parameters. Here, we present a consistent suite of 19F-based CPMG, on-resonance R1ρ and off-resonance R1ρ RD experiments. We validate these experiments by studying the unfolding transition of a 7.5 kDa cold shock protein. Furthermore we show that the 19F RD experiments are applicable to very large molecular machines by quantifying dynamics in the 360 kDa half-proteasome. Our approach significantly extends the timescale of chemical exchange that can be studied with 19F RD, adds robustness to the extraction of exchange parameters and can determine the absolute chemical shifts of excited states. Importantly, due to the simplicity of 19F NMR spectra, it is possible to record complete datasets within hours on samples that are of very low costs. This makes the presented experiments ideally suited to complement static structural information from cryo-EM and X-ray crystallography with insights into functionally relevant motions.
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Affiliation(s)
- Jan H Overbeck
- Department of Biophysics I, Regensburg Center for Biochemistry, University of Regensburg, 93053, Regensburg, Germany
| | - Werner Kremer
- Department of Biophysics I, Regensburg Center for Biochemistry, University of Regensburg, 93053, Regensburg, Germany
| | - Remco Sprangers
- Department of Biophysics I, Regensburg Center for Biochemistry, University of Regensburg, 93053, Regensburg, Germany.
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18
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Baisden JT, Boyer JA, Zhao B, Hammond SM, Zhang Q. Visualizing a protonated RNA state that modulates microRNA-21 maturation. Nat Chem Biol 2020; 17:80-88. [PMID: 33106660 DOI: 10.1038/s41589-020-00667-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 08/02/2020] [Accepted: 09/02/2020] [Indexed: 01/09/2023]
Abstract
MicroRNAs are evolutionarily conserved small, noncoding RNAs that regulate diverse biological processes. Due to their essential regulatory roles, microRNA biogenesis is tightly regulated, where protein factors are often found to interact with specific primary and precursor microRNAs for regulation. Here, using NMR relaxation dispersion spectroscopy and mutagenesis, we reveal that the precursor of oncogenic microRNA-21 exists as a pH-dependent ensemble that spontaneously reshuffles the secondary structure of the entire apical stem-loop region, including the Dicer cleavage site. We show that the alternative excited conformation transiently sequesters the bulged adenine into a noncanonical protonated A+-G mismatch, conferring a substantial enhancement in Dicer processing over its ground conformational state. These results indicate that microRNA maturation efficiency may be encoded in the intrinsic dynamic ensemble of primary and precursor microRNAs, providing a potential means of regulating microRNA biogenesis in response to environmental and cellular stimuli.
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Affiliation(s)
- Jared T Baisden
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joshua A Boyer
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bo Zhao
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Scott M Hammond
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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19
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Tiwari VP, Vallurupalli P. A CEST NMR experiment to obtain glycine 1H α chemical shifts in 'invisible' minor states of proteins. JOURNAL OF BIOMOLECULAR NMR 2020; 74:443-455. [PMID: 32696193 DOI: 10.1007/s10858-020-00336-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 07/11/2020] [Indexed: 06/11/2023]
Abstract
Chemical exchange saturation transfer (CEST) experiments are routinely used to study protein conformational exchange between a 'visible' major state and 'invisible' minor states because they can detect minor states with lifetimes varying from ~ 3 to ~ 100 ms populated to just ~ 0.5%. Consequently several 1H, 15N and 13C CEST experiments have been developed to study exchange and obtain minor state chemical shifts at almost all backbone and sidechain sites in proteins. Conspicuously missing from this extensive set of CEST experiments is a 1H CEST experiment to study exchange at glycine (Gly) 1Hα sites as the existing 1H CEST experiments that have been designed to study dynamics in amide 1H-15N spin systems and methyl 13CH3 groups with three equivalent protons while suppressing 1H-1H NOE induced dips are not suitable for studying exchange in methylene 13CH2 groups with inequivalent protons. Here a Gly 1Hα CEST experiment to obtain the minor state Gly 1Hα chemical shifts is presented. The utility of this experiment is demonstrated on the L99A cavity mutant of T4 Lysozyme (T4L L99A) that undergoes conformational exchange between two compact conformers. The CEST derived minor state Gly 1Hα chemical shifts of T4L L99A are in agreement with those obtained previously using CPMG techniques. The experimental strategy presented here can also be used to obtain methylene proton minor state chemical shifts from protein sidechain and nucleic acid backbone sites.
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Affiliation(s)
- Ved Prakash Tiwari
- Tata Institute of Fundamental Research, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad, Telangana, 500107, India
| | - Pramodh Vallurupalli
- Tata Institute of Fundamental Research, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad, Telangana, 500107, India.
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20
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Rangadurai A, Shi H, Al-Hashimi HM. Extending the Sensitivity of CEST NMR Spectroscopy to Micro-to-Millisecond Dynamics in Nucleic Acids Using High-Power Radio-Frequency Fields. Angew Chem Int Ed Engl 2020; 59:11262-11266. [PMID: 32168407 PMCID: PMC7857695 DOI: 10.1002/anie.202000493] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/07/2020] [Indexed: 11/10/2022]
Abstract
Biomolecules undergo motions on the micro-to-millisecond timescale to adopt low-populated transient states that play important roles in folding, recognition, and catalysis. NMR techniques, such as Carr-Purcell-Meiboom-Gill (CPMG), chemical exchange saturation transfer (CEST), and R1ρ are the most commonly used methods for characterizing such transitions at atomic resolution under solution conditions. CPMG and CEST are most effective at characterizing motions on the millisecond timescale. While some implementations of the R1ρ experiment are more broadly sensitive to motions on the micro-to-millisecond timescale, they entail the use of selective irradiation schemes and inefficient 1D data acquisition methods. Herein, we show that high-power radio-frequency fields can be used in CEST experiments to extend the sensitivity to faster motions on the micro-to-millisecond timescale. Given the ease of implementing high-power fields in CEST, this should make it easier to characterize micro-to-millisecond dynamics in biomolecules.
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Affiliation(s)
- Atul Rangadurai
- Department of Biochemistry, Duke University, 229, Nanaline Duke Building, 307 Research Drive, Durham, NC, 27710, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University, 229, Nanaline Duke Building, 307 Research Drive, Durham, NC, 27710, USA
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
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21
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Rangadurai A, Shi H, Al‐Hashimi HM. Extending the Sensitivity of CEST NMR Spectroscopy to Micro‐to‐Millisecond Dynamics in Nucleic Acids Using High‐Power Radio‐Frequency Fields. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Atul Rangadurai
- Department of Biochemistry Duke University 229, Nanaline Duke Building, 307 Research Drive Durham NC 27710 USA
| | - Honglue Shi
- Department of Chemistry Duke University Durham NC 27708 USA
| | - Hashim M. Al‐Hashimi
- Department of Biochemistry Duke University 229, Nanaline Duke Building, 307 Research Drive Durham NC 27710 USA
- Department of Chemistry Duke University Durham NC 27708 USA
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22
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Abstract
RNA recognition frequently results in conformational changes that optimize intermolecular binding. As a consequence, the overall binding affinity of RNA to its binding partners depends not only on the intermolecular interactions formed in the bound state but also on the energy cost associated with changing the RNA conformational distribution. Measuring these "conformational penalties" is, however, challenging because bound RNA conformations tend to have equilibrium populations in the absence of the binding partner that fall outside detection by conventional biophysical methods. In this study we employ as a model system HIV-1 TAR RNA and its interaction with the ligand argininamide (ARG), a mimic of TAR's cognate protein binding partner, the transactivator Tat. We use NMR chemical shift perturbations and relaxation dispersion in combination with Bayesian inference to develop a detailed thermodynamic model of coupled conformational change and ligand binding. Starting from a comprehensive 12-state model of the equilibrium, we estimate the energies of six distinct detectable thermodynamic states that are not accessible by currently available methods. Our approach identifies a minimum of four RNA intermediates that differ in terms of the TAR conformation and ARG occupancy. The dominant bound TAR conformation features two bound ARG ligands and has an equilibrium population in the absence of ARG that is below detection limit. Consequently, even though ARG binds to TAR with an apparent overall weak affinity (Kdapp ≈ 0.2 mM), it binds the prefolded conformation with a Kd in the nM range. Our results show that conformational penalties can be major determinants of RNA-ligand binding affinity as well as a source of binding cooperativity, with important implications for a predictive understanding of how RNA is recognized and for RNA-targeted drug discovery.
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Affiliation(s)
- Nicole I. Orlovsky
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Terrence G. Oas
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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23
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Abstract
RNA molecules fold into complex three-dimensional structures that sample alternate conformations ranging from minor differences in tertiary structure dynamics to major differences in secondary structure. This allows them to form entirely different substructures with each population potentially giving rise to a distinct biological outcome. The substructures can be partitioned along an existing energy landscape given a particular static cellular cue or can be shifted in response to dynamic cues such as ligand binding. We review a few key examples of RNA molecules that sample alternate conformations and how these are capitalized on for control of critical regulatory functions.
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Affiliation(s)
- Marie Teng-Pei Wu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Victoria D'Souza
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
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24
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Zhao B, Baisden JT, Zhang Q. Probing excited conformational states of nucleic acids by nitrogen CEST NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2020; 310:106642. [PMID: 31785475 PMCID: PMC6934915 DOI: 10.1016/j.jmr.2019.106642] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 10/30/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
Characterizing low-populated and short-lived excited conformational states has become increasingly important for understanding mechanisms of RNA function. Interconversion between RNA ground and excited conformational states often involves base pairing rearrangements that lead to changes in the hydrogen-bond network. Here, we present two 15N chemical exchange saturation transfer (CEST) NMR experiments that utilize protonated and non-protonated nitrogens, which are key hydrogen-bond donors and acceptors, for characterizing excited conformational states in RNA. We demonstrated these approaches on the B. Cereus fluoride riboswitch, where 15N CEST profiles complement 13C CEST profiles in depicting a potential pathway for ligand-dependent allosteric regulation of the excited conformational state of the fluoride riboswitch.
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Affiliation(s)
- Bo Zhao
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jared T Baisden
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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25
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Shi H, Liu B, Nussbaumer F, Rangadurai A, Kreutz C, Al-Hashimi HM. NMR Chemical Exchange Measurements Reveal That N6-Methyladenosine Slows RNA Annealing. J Am Chem Soc 2019; 141:19988-19993. [PMID: 31826614 DOI: 10.1021/jacs.9b10939] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N6-Methyladenosine (m6A) is an abundant epitranscriptomic modification that plays important roles in many aspects of RNA metabolism. While m6A is thought to mainly function by recruiting reader proteins to specific RNA sites, the modification can also reshape RNA-protein and RNA-RNA interactions by altering RNA structure mainly by destabilizing base pairing. Little is known about how m6A and other epitranscriptomic modifications might affect the kinetic rates of RNA folding and other conformational transitions that are also important for cellular activity. Here, we used NMR R1ρ relaxation dispersion and chemical exchange saturation transfer to noninvasively and site-specifically measure nucleic acid hybridization kinetics. The methodology was validated on two DNA duplexes and then applied to examine how a single m6A alters the hybridization kinetics in two RNA duplexes. The results show that m6A minimally impacts the rate constant for duplex dissociation, changing koff by ∼1-fold but significantly slows the rate of duplex annealing, decreasing kon by ∼7-fold. A reduction in the annealing rate was observed robustly for two different sequence contexts at different temperatures, both in the presence and absence of Mg2+. We propose that rotation of the N6-methyl group from the preferred syn conformation in the unpaired nucleotide to the energetically disfavored anti conformation required for Watson-Crick pairing is responsible for the reduced annealing rate. The results help explain why in mRNA m6A slows down tRNA selection and more generally suggest that m6A may exert cellular functions by reshaping the kinetics of RNA conformational transitions.
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Affiliation(s)
- Honglue Shi
- Department of Chemistry , Duke University , Durham , North Carolina 27710 , United States
| | - Bei Liu
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Felix Nussbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , 6020 Innsbruck , Austria
| | - Atul Rangadurai
- Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , 6020 Innsbruck , Austria
| | - Hashim M Al-Hashimi
- Department of Chemistry , Duke University , Durham , North Carolina 27710 , United States.,Department of Biochemistry , Duke University School of Medicine , Durham , North Carolina 27710 , United States
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26
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Zhang K, Frank AT. Conditional Prediction of Ribonucleic Acid Secondary Structure Using Chemical Shifts. J Phys Chem B 2019; 124:470-478. [DOI: 10.1021/acs.jpcb.9b09814] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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27
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Marušič M, Schlagnitweit J, Petzold K. RNA Dynamics by NMR Spectroscopy. Chembiochem 2019; 20:2685-2710. [PMID: 30997719 PMCID: PMC6899578 DOI: 10.1002/cbic.201900072] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/12/2019] [Indexed: 12/22/2022]
Abstract
An ever-increasing number of functional RNAs require a mechanistic understanding. RNA function relies on changes in its structure, so-called dynamics. To reveal dynamic processes and higher energy structures, new NMR methods have been developed to elucidate these dynamics in RNA with atomic resolution. In this Review, we provide an introduction to dynamics novices and an overview of methods that access most dynamic timescales, from picoseconds to hours. Examples are provided as well as insight into theory, data acquisition and analysis for these different methods. Using this broad spectrum of methodology, unprecedented detail and invisible structures have been obtained and are reviewed here. RNA, though often more complicated and therefore neglected, also provides a great system to study structural changes, as these RNA structural changes are more easily defined-Lego like-than in proteins, hence the numerous revelations of RNA excited states.
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Affiliation(s)
- Maja Marušič
- Department of Medical Biochemistry and BiophysicsKarolinska InstitutetSolnavägen 917177StockholmSweden
| | - Judith Schlagnitweit
- Department of Medical Biochemistry and BiophysicsKarolinska InstitutetSolnavägen 917177StockholmSweden
| | - Katja Petzold
- Department of Medical Biochemistry and BiophysicsKarolinska InstitutetSolnavägen 917177StockholmSweden
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Rangadurai A, Szymaski ES, Kimsey IJ, Shi H, Al-Hashimi HM. Characterizing micro-to-millisecond chemical exchange in nucleic acids using off-resonance R 1ρ relaxation dispersion. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 112-113:55-102. [PMID: 31481159 PMCID: PMC6727989 DOI: 10.1016/j.pnmrs.2019.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 05/10/2023]
Abstract
This review describes off-resonance R1ρ relaxation dispersion NMR methods for characterizing microsecond-to-millisecond chemical exchange in uniformly 13C/15N labeled nucleic acids in solution. The review opens with a historical account of key developments that formed the basis for modern R1ρ techniques used to study chemical exchange in biomolecules. A vector model is then used to describe the R1ρ relaxation dispersion experiment, and how the exchange contribution to relaxation varies with the amplitude and frequency offset of an applied spin-locking field, as well as the population, exchange rate, and differences in chemical shifts of two exchanging species. Mathematical treatment of chemical exchange based on the Bloch-McConnell equations is then presented and used to examine relaxation dispersion profiles for more complex exchange scenarios including three-state exchange. Pulse sequences that employ selective Hartmann-Hahn cross-polarization transfers to excite individual 13C or 15N spins are then described for measuring off-resonance R1ρ(13C) and R1ρ(15N) in uniformly 13C/15N labeled DNA and RNA samples prepared using commercially available 13C/15N labeled nucleotide triphosphates. Approaches for analyzing R1ρ data measured at a single static magnetic field to extract a full set of exchange parameters are then presented that rely on numerical integration of the Bloch-McConnell equations or the use of algebraic expressions. Methods for determining structures of nucleic acid excited states are then reviewed that rely on mutations and chemical modifications to bias conformational equilibria, as well as structure-based approaches to calculate chemical shifts. Applications of the methodology to the study of DNA and RNA conformational dynamics are reviewed and the biological significance of the exchange processes is briefly discussed.
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Affiliation(s)
- Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Eric S Szymaski
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Isaac J Kimsey
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA; Nymirum, 4324 S. Alston Avenue, Durham, NC 27713, USA(1)
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, NC 27710, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA; Department of Chemistry, Duke University, Durham, NC 27710, USA.
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Thompson RD, Baisden JT, Zhang Q. NMR characterization of RNA small molecule interactions. Methods 2019; 167:66-77. [PMID: 31128236 DOI: 10.1016/j.ymeth.2019.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 01/25/2023] Open
Abstract
Exciting discoveries of naturally occurring ligand-sensing and disease-linked noncoding RNAs have promoted significant interests in understanding RNA-small molecule interactions. NMR spectroscopy is a powerful tool for characterizing intermolecular interactions. In this review, we describe protocols and approaches for applying NMR spectroscopy to investigate interactions between RNA and small molecules. We review protocols for RNA sample preparation, methods for identifying RNA-binding small molecules, approaches for mapping RNA-small molecule interactions, determining complex structures, and characterizing binding kinetics. We hope this review will provide a guideline to streamline NMR applications in studying RNA-small molecule interactions, facilitating both basic mechanistic understandings of RNA functions and translational efforts in developing RNA-targeted therapeutics.
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Affiliation(s)
- Rhese D Thompson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jared T Baisden
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Zhang H, Keane SC. Advances that facilitate the study of large RNA structure and dynamics by nuclear magnetic resonance spectroscopy. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 10:e1541. [PMID: 31025514 PMCID: PMC7169810 DOI: 10.1002/wrna.1541] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/18/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022]
Abstract
The characterization of functional yet nonprotein coding (nc) RNAs has expanded the role of RNA in the cell from a passive player in the central dogma of molecular biology to an active regulator of gene expression. The misregulation of ncRNA function has been linked with a variety of diseases and disorders ranging from cancers to neurodegeneration. However, a detailed molecular understanding of how ncRNAs function has been limited; due, in part, to the difficulties associated with obtaining high-resolution structures of large RNAs. Tertiary structure determination of RNA as a whole is hampered by various technical challenges, all of which are exacerbated as the size of the RNA increases. Namely, RNAs tend to be highly flexible and dynamic molecules, which are difficult to crystallize. Biomolecular nuclear magnetic resonance (NMR) spectroscopy offers a viable alternative to determining the structure of large RNA molecules that do not readily crystallize, but is itself hindered by some technical limitations. Recently, a series of advancements have allowed the biomolecular NMR field to overcome, at least in part, some of these limitations. These advances include improvements in sample preparation strategies as well as methodological improvements. Together, these innovations pave the way for the study of ever larger RNA molecules that have important biological function. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems.
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Affiliation(s)
- Huaqun Zhang
- Biophysics Program, University of Michigan, Ann Arbor, Michigan
| | - Sarah C Keane
- Biophysics Program, University of Michigan, Ann Arbor, Michigan.,Department of Chemistry, University of Michigan, Ann Arbor, Michigan
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31
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Eubanks CS, Zhao B, Patwardhan NN, Thompson RD, Zhang Q, Hargrove AE. Visualizing RNA Conformational Changes via Pattern Recognition of RNA by Small Molecules. J Am Chem Soc 2019; 141:5692-5698. [DOI: 10.1021/jacs.8b09665] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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32
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Tiwari VP, Pandit S, Vallurupalli P. Exchangeable deuterons introduce artifacts in amide 15N CEST experiments used to study protein conformational exchange. JOURNAL OF BIOMOLECULAR NMR 2019; 73:43-48. [PMID: 30661150 DOI: 10.1007/s10858-018-00223-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
Protein molecules sample different conformations in solution and characterizing these conformations is crucial to understanding protein function. 15N CEST experiments are now routinely used to study slow conformational exchange of protein molecules between a 'visible' major state and 'invisible' minor states. These experiments have also been adapted to measure the solvent exchange rates of amide protons by exploiting the one bond deuterium isotope effect on the amide 15N chemical shifts. However at moderately high temperatures (~ 50 °C) that are sometimes required to populate protein minor conformers to levels (~ 1%) that can be detected by CEST experiments solvent H/D exchange can lead to 'dips' in low B115N CEST profiles that can be wrongly assigned to the conformational exchange process being characterized. This is demonstrated in the case of ~ 18 kDa T4 Lysozyme (T4L) at 50 °C and the ~ 11 kDa E. coli hibernation promoting factor (HPF) at 52 °C. This problem is trivially solved by eliminating the exchangeable deuterons in the solvent by using either an external D2O lock or by using a small amount (~ 1-3%) of a molecule like d6-DMSO that does not contain exchangeable deuterons to lock the spectrometer.
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Affiliation(s)
- Ved Prakash Tiwari
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad, Telangana, 500107, India
| | - Subhendu Pandit
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad, Telangana, 500107, India
| | - Pramodh Vallurupalli
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad, Telangana, 500107, India.
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33
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Eubanks CS, Hargrove AE. RNA Structural Differentiation: Opportunities with Pattern Recognition. Biochemistry 2018; 58:199-213. [PMID: 30513196 DOI: 10.1021/acs.biochem.8b01090] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Our awareness and appreciation of the many regulatory roles of RNA have dramatically increased in the past decade. This understanding, in addition to the impact of RNA in many disease states, has renewed interest in developing selective RNA-targeted small molecule probes. However, the fundamental guiding principles in RNA molecular recognition that could accelerate these efforts remain elusive. While high-resolution structural characterization can provide invaluable insight, examples of well-characterized RNA structures, not to mention small molecule:RNA complexes, remain limited. This Perspective provides an overview of the current techniques used to understand RNA molecular recognition when high-resolution structural information is unavailable. We will place particular emphasis on a new method, pattern recognition of RNA with small molecules (PRRSM), that provides rapid insight into critical components of RNA recognition and differentiation by small molecules as well as into RNA structural features.
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Affiliation(s)
- Christopher S Eubanks
- Department of Chemistry , Duke University , Durham , North Carolina 27708-0354 , United States
| | - Amanda E Hargrove
- Department of Chemistry , Duke University , Durham , North Carolina 27708-0354 , United States
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34
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Abstract
The phenomenon of chemical or conformational exchange in NMR spectroscopy has enabled detailed characterization of time-dependent aspects of biomolecular function, including folding, molecular recognition, allostery, and catalysis, on timescales from microsecond to second. Importantly, NMR methods based on a variety of spin relaxation parameters have been developed that provide quantitative information on interconversion kinetics, thermodynamic properties, and structural features of molecular states populated to a fraction of a percent at equilibrium and otherwise unobservable by other NMR approaches. The ongoing development of more sophisticated experimental techniques and the necessity to apply these methods to larger and more complex molecular systems engenders a corresponding need for theoretical advances describing such techniques and facilitating data analysis in applications. This review surveys current aspects of the theory of chemical exchange, as utilized in ZZ-exchange; Hahn and Carr-Purcell-Meiboom-Gill (CPMG) spin-echo; and R1ρ, chemical exchange saturation transfer (CEST), and dark state saturation transfer (DEST) spin-locking experiments. The review emphasizes theoretical results for kinetic topologies with more than two interconverting states, both to obtain compact analytical forms suitable for data analysis and to establish conditions for distinguishability between alternative kinetic schemes.
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Affiliation(s)
- Arthur G Palmer
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States.
| | - Hans Koss
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States
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35
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White NA, Sumita M, Marquez VE, Hoogstraten CG. Coupling between conformational dynamics and catalytic function at the active site of the lead-dependent ribozyme. RNA (NEW YORK, N.Y.) 2018; 24:1542-1554. [PMID: 30111534 PMCID: PMC6191710 DOI: 10.1261/rna.067579.118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/02/2018] [Indexed: 06/08/2023]
Abstract
In common with other self-cleaving RNAs, the lead-dependent ribozyme (leadzyme) undergoes dynamic fluctuations to a chemically activated conformation. We explored the connection between conformational dynamics and self-cleavage function in the leadzyme using a combination of NMR spin-relaxation analysis of ribose groups and conformational restriction via chemical modification. The functional studies were performed with a North-methanocarbacytidine modification that prevents fluctuations to C2'-endo conformations while maintaining an intact 2'-hydroxyl nucleophile. Spin-relaxation data demonstrate that the active-site Cyt-6 undergoes conformational exchange attributed to sampling of a minor C2'-endo state with an exchange lifetime on the order of microseconds to tens of microseconds. A conformationally restricted species in which the fluctuations to the minor species are interrupted shows a drastic decrease in self-cleavage activity. Taken together, these data indicate that dynamic sampling of a minor species at the active site of this ribozyme, and likely of related naturally occurring motifs, is strongly coupled to catalytic function. The combination of NMR dynamics analysis with functional probing via conformational restriction is a general methodology for dissecting dynamics-function relationships in RNA.
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Affiliation(s)
- Neil A White
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Minako Sumita
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Victor E Marquez
- Chemical Biology Laboratory, Molecular Discovery Program, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, USA
| | - Charles G Hoogstraten
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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36
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Niu X, Ding J, Zhang W, Li Q, Hu Y, Jin C. Residue selective 15N CEST and CPMG experiments for studies of millisecond timescale protein dynamics. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 293:47-55. [PMID: 29890486 DOI: 10.1016/j.jmr.2018.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/27/2018] [Accepted: 05/30/2018] [Indexed: 06/08/2023]
Abstract
Proteins are intrinsically dynamic molecules and undergo exchanges among multiple conformations to perform biological functions. The CPMG relaxation dispersion and CEST experiments are two important solution NMR techniques for characterizing the conformational exchange processes on the millisecond timescale. Traditional pseudo 3D 15N CEST and CPMG experiments have certain limitations in their applications. For example, both experiments have low sensitivity for broadened resonances, and the process of optimizing sample conditions and experimental parameters are often time consuming. To overcome these limitations, we herein present a new set of residue selective 15N CEST and CPMG pulse sequences by employing the Hartmann-Hahn cross-polarization transfer of magnetization in both 1D and 2D schemes. Combined with frequency labeling in the indirect dimension using only a small number of increments, the pulse sequences in the 2D scheme can be applied on resonances in overlapped regions of the 1H-15N HSQC spectrum. The pulse sequences were further applied on several proteins, demonstrating their advantages over the traditional CEST and CPMG experiments under specific circumstances.
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Affiliation(s)
- Xiaogang Niu
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
| | - Jienv Ding
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Life Sciences, Peking University, Beijing, China
| | - Wenbo Zhang
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Life Sciences, Peking University, Beijing, China
| | - Qianwen Li
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Life Sciences, Peking University, Beijing, China
| | - Yunfei Hu
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China; College of Chemistry and Molecular Engineering, Peking University, Beijing, China; College of Life Sciences, Peking University, Beijing, China.
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37
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Yuwen T, Bouvignies G, Kay LE. Exploring methods to expedite the recording of CEST datasets using selective pulse excitation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 292:1-7. [PMID: 29753980 DOI: 10.1016/j.jmr.2018.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Chemical Exchange Saturation Transfer (CEST) has emerged as a powerful tool for studies of biomolecular conformational exchange involving the interconversion between a major, visible conformer and one or more minor, invisible states. Applications typically entail recording a large number of 2D datasets, each of which differs in the position of a weak radio frequency field, so as to generate a CEST profile for each nucleus from which the chemical shifts of spins in the invisible state(s) are obtained. Here we compare a number of band-selective CEST schemes for speeding up the process using either DANTE or cosine-modulated excitation approaches. We show that while both are essentially identical for applications such as 15N CEST, in cases where the probed spins are dipolar or scalar coupled to other like spins there can be advantages for the cosine-excitation scheme.
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Affiliation(s)
- Tairan Yuwen
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
| | - Guillaume Bouvignies
- Laboratoire des biomolécules, LBM, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Hospital for Sick Children, Program in Molecular Medicine, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
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38
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Strebitzer E, Nußbaumer F, Kremser J, Tollinger M, Kreutz C. Studying sparsely populated conformational states in RNA combining chemical synthesis and solution NMR spectroscopy. Methods 2018; 148:39-47. [PMID: 29753787 DOI: 10.1016/j.ymeth.2018.05.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/07/2018] [Indexed: 12/18/2022] Open
Abstract
Using chemical synthesis and solution NMR spectroscopy, RNA structural ensembles including a major ground state and minor populated excited states can be studied at atomic resolution. In this work, atom-specific 13C labeled RNA building blocks - a 5-13C-uridine and a 2,8-13C2-adenosine building block - are used to introduce isolated 13C-1H-spin topologies into a target RNA to probe such structural ensembles via NMR spectroscopy. First, the 5-13C-uridine 2'-O-TBDMS-phosphoramidite building block was introduced into a 21 nucleotide (nt) tP5c stem construct of the tP5abc subdomain of the Tetrahymena group I ribozyme. Then, the 2,8-13C2-adenosine 2'-O-TBDMS-phosphoramidite building block was incorporated into a 9 kDa and a 15 kD construct derived from the epsilon (ε) RNA element of the duck Hepatitis B virus. The 2,8-13C2-adenosine resonances of the 9 kDa 28 nt sequence could be mapped to the full-length 53 nt construct. The isolated NMR active nuclei pairs were used to probe for low populated excited states (<10%) via 13C-Carr-Purcell-Meiboom-Gill (CPMG)-relaxation dispersion NMR spectroscopy. The 13C-CPMG relaxation dispersion experiment recapitulated a secondary structure switching event in the P5c hairpin of the group I intron construct previously revealed by 15N relaxation dispersion experiments. In the ε-HBV RNA an unfolding event occurring on the millisecond time scale was found in the upper stem in-line with earlier observations. This unpaired conformational state is presumed to be important for the binding of the epsilon reverse transcriptase (RT) enzyme. Thus, a full description of an RNA's folding landscape helps to obtain a deeper understanding of its function, as these high energy conformational states often represent functionally important intermediates involved in (un)folding or ribozyme catalysis.
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Affiliation(s)
- Elisabeth Strebitzer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Johannes Kremser
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Martin Tollinger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
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Yang X, Shen S, Guo L, Tan J, Lei H, Wu J, Zhao L, Xiong T, Wu Y, Cheng Y, Zhang Y. An Enzyme-Responsive “Turn-on” Fluorescence Polymeric Superamphiphile as a Potential Visualizable Phosphate Prodrug Delivery Vehicle. Macromol Biosci 2018; 18:e1800045. [DOI: 10.1002/mabi.201800045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 03/12/2018] [Indexed: 01/08/2023]
Affiliation(s)
- Xi Yang
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Shihong Shen
- Key Laboratory of Biomedical Information Engineering of Education Ministry; School of Life Science and Technology; Xi'an Jiaotong University; Xi'an 710049 China
| | - Li Guo
- State Key Laboratory of Electrical Insulation and Power Equipment; Centre for Plasma Biomedicine; Xi'an Jiaotong University; Xi'an 710049 China
| | - Jidong Tan
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Henxin Lei
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Jianghan Wu
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Lei Zhao
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Tao Xiong
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Youshen Wu
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Yilong Cheng
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
| | - Yanfeng Zhang
- Department of Applied Chemistry; School of Science; MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 China
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40
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Chen B, Longhini AP, Nußbaumer F, Kreutz C, Dinman JD, Dayie TK. CCR5 RNA Pseudoknots: Residue and Site-Specific Labeling correlate Internal Motions with microRNA Binding. Chemistry 2018; 24:5462-5468. [PMID: 29412477 PMCID: PMC7640883 DOI: 10.1002/chem.201705948] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/29/2018] [Indexed: 12/31/2022]
Abstract
Conformational dynamics of RNA molecules play a critical role in governing their biological functions. Measurements of RNA dynamic behavior sheds important light on sites that interact with their binding partners or cellular stimulators. However, such measurements using solution-state NMR are difficult for large RNA molecules (>70 nt; nt=nucleotides) owing to severe spectral overlap, homonuclear 13 C scalar couplings, and line broadening. Herein, a strategic combination of solid-phase synthesis, site-specific isotopic labeled phosphoramidites, and enzymatic ligation is introduced. This approach allowed the position-specific insertion of isotopic probes into a 96 nt CCR5 RNA fragment. Accurate measurements of functional dynamics using the Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion (RD) experiments enabled extraction of the exchange rates and populations of this RNA. NMR chemical shift perturbation analysis of the RNA/microRNA-1224 complex indicated that A90-C1' of the pseudoknot exhibits similar changes in chemical shift observed in the excited state. This work demonstrates the general applicability of a NMR-labeling strategy to probe functional RNA structural dynamics.
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Affiliation(s)
- Bin Chen
- Department of Cell Biology and Molecular Genetics, University of Maryland, 4062 Campus Dr., College Park, MD, 20742, USA
- Center for Biomolecular Structure & Organization, Department of Chemistry & Biochemistry, University of Maryland, 8314 Paint Branch Dr., College Park, MD, 20782, USA
| | - Andrew P Longhini
- Center for Biomolecular Structure & Organization, Department of Chemistry & Biochemistry, University of Maryland, 8314 Paint Branch Dr., College Park, MD, 20782, USA
| | - Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences, Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences, Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Jonathan D Dinman
- Department of Cell Biology and Molecular Genetics, University of Maryland, 4062 Campus Dr., College Park, MD, 20742, USA
| | - T Kwaku Dayie
- Center for Biomolecular Structure & Organization, Department of Chemistry & Biochemistry, University of Maryland, 8314 Paint Branch Dr., College Park, MD, 20782, USA
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41
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Shi H, Clay MC, Rangadurai A, Sathyamoorthy B, Case DA, Al-Hashimi HM. Atomic structures of excited state A-T Hoogsteen base pairs in duplex DNA by combining NMR relaxation dispersion, mutagenesis, and chemical shift calculations. JOURNAL OF BIOMOLECULAR NMR 2018; 70:229-244. [PMID: 29675775 PMCID: PMC6048961 DOI: 10.1007/s10858-018-0177-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 03/29/2018] [Indexed: 05/20/2023]
Abstract
NMR relaxation dispersion studies indicate that in canonical duplex DNA, Watson-Crick base pairs (bps) exist in dynamic equilibrium with short-lived low abundance excited state Hoogsteen bps. N1-methylated adenine (m1A) and guanine (m1G) are naturally occurring forms of damage that stabilize Hoogsteen bps in duplex DNA. NMR dynamic ensembles of DNA duplexes with m1A-T Hoogsteen bps reveal significant changes in sugar pucker and backbone angles in and around the Hoogsteen bp, as well as kinking of the duplex towards the major groove. Whether these structural changes also occur upon forming excited state Hoogsteen bps in unmodified duplexes remains to be established because prior relaxation dispersion probes provided limited information regarding the sugar-backbone conformation. Here, we demonstrate measurements of C3' and C4' spin relaxation in the rotating frame (R1ρ) in uniformly 13C/15N labeled DNA as sensitive probes of the sugar-backbone conformation in DNA excited states. The chemical shifts, combined with structure-based predictions using an automated fragmentation quantum mechanics/molecular mechanics method, show that the dynamic ensemble of DNA duplexes containing m1A-T Hoogsteen bps accurately model the excited state Hoogsteen conformation in two different sequence contexts. Formation of excited state A-T Hoogsteen bps is accompanied by changes in sugar-backbone conformation that allow the flipped syn adenine to form hydrogen-bonds with its partner thymine and this in turn results in overall kinking of the DNA toward the major groove. Results support the assignment of Hoogsteen bps as the excited state observed in canonical duplex DNA, provide an atomic view of DNA dynamics linked to formation of Hoogsteen bps, and lay the groundwork for a potentially general strategy for solving structures of nucleic acid excited states.
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Affiliation(s)
- Honglue Shi
- Department of Chemistry, Duke University, Durham, NC 27710, USA
| | - Mary C. Clay
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Atul Rangadurai
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Bharathwaj Sathyamoorthy
- Department of Chemistry, Duke University, Durham, NC 27710, USA
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - David A. Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
- To whom correspondence should be addressed. Telephone: (919) 660-1113, or
| | - Hashim M. Al-Hashimi
- Department of Chemistry, Duke University, Durham, NC 27710, USA
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- To whom correspondence should be addressed. Telephone: (919) 660-1113, or
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42
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Wu Q, Fenton BA, Wojtaszek JL, Zhou P. Probing the excited-state chemical shifts and exchange parameters by nitrogen-decoupled amide proton chemical exchange saturation transfer (HN dec-CEST). Chem Commun (Camb) 2018; 53:8541-8544. [PMID: 28707688 DOI: 10.1039/c7cc05021f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
CEST-NMR spectroscopy is a powerful tool for probing the conformational dynamics of macromolecules. We present a HNdec-CEST experiment that simplifies the relaxation matrix, reduces fitting parameters, and enhances signal resolution. Importantly, fitting of HNdec-CEST profiles enables robust extraction of exchange rates as well as excited-state chemical shifts and populations.
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Affiliation(s)
- Qinglin Wu
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Benjamin A Fenton
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Jessica L Wojtaszek
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
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43
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Lokesh N, Seegerer A, Hioe J, Gschwind RM. Chemical Exchange Saturation Transfer in Chemical Reactions: A Mechanistic Tool for NMR Detection and Characterization of Transient Intermediates. J Am Chem Soc 2018; 140:1855-1862. [PMID: 29336150 PMCID: PMC6301330 DOI: 10.1021/jacs.7b12343] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
The low sensitivity of NMR and transient
key intermediates below
detection limit are the central problems studying reaction mechanisms
by NMR. Sensitivity can be enhanced by hyperpolarization techniques
such as dynamic nuclear polarization or the incorporation/interaction
of special hyperpolarized molecules. However, all of these techniques
require special equipment, are restricted to selective reactions,
or undesirably influence the reaction pathways. Here, we apply the
chemical exchange saturation transfer (CEST) technique for the first
time to NMR detect and characterize previously unobserved transient
reaction intermediates in organocatalysis. The higher sensitivity
of CEST and chemical equilibria present in the reaction pathway are
exploited to access population and kinetics information on low populated
intermediates. The potential of the method is demonstrated on the
proline-catalyzed enamine formation for unprecedented in situ detection of a DPU stabilized zwitterionic iminium species, the
elusive key intermediate between enamine and oxazolidinones. The quantitative
analysis of CEST data at 250 K revealed the population ratio of [Z-iminium]/[exo-oxazolidinone] 0.02, relative
free energy +8.1 kJ/mol (calculated +7.3 kJ/mol), and free energy
barrier of +45.9 kJ/mol (ΔG⧧calc.(268 K) = +42.2 kJ/mol) for Z-iminium
→ exo-oxazolidinone. The findings underpin
the iminium ion participation in enamine formation pathway corroborating
our earlier theoretical prediction and help in better understanding.
The reliability of CEST is validated using 1D EXSY-build-up techniques
at low temperature (213 K). The CEST method thus serves as a new tool
for mechanistic investigations in organocatalysis to access key information,
such as chemical shifts, populations, and reaction kinetics of intermediates
below the standard NMR detection limit.
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Affiliation(s)
- N Lokesh
- Institute of Organic Chemistry, University of Regensburg , D-93053 Regensburg, Germany
| | - Andreas Seegerer
- Institute of Organic Chemistry, University of Regensburg , D-93053 Regensburg, Germany
| | - Johnny Hioe
- Institute of Organic Chemistry, University of Regensburg , D-93053 Regensburg, Germany
| | - Ruth M Gschwind
- Institute of Organic Chemistry, University of Regensburg , D-93053 Regensburg, Germany
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44
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Williams B, Zhao B, Tandon A, Ding F, Weeks KM, Zhang Q, Dokholyan NV. Structure modeling of RNA using sparse NMR constraints. Nucleic Acids Res 2018; 45:12638-12647. [PMID: 29165648 PMCID: PMC5728392 DOI: 10.1093/nar/gkx1058] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/18/2017] [Indexed: 01/04/2023] Open
Abstract
RNAs fold into distinct molecular conformations that are often essential for their functions. Accurate structure modeling of complex RNA motifs, including ubiquitous non-canonical base pairs and pseudoknots, remains a challenge. Here, we present an NMR-guided all-atom discrete molecular dynamics (DMD) platform, iFoldNMR, for rapid and accurate structure modeling of complex RNAs. We show that sparse distance constraints from imino resonances, which can be readily obtained from routine NMR experiments and easier to compile than laborious assignments of non-solvent-exchangeable protons, are sufficient to direct a DMD search for low-energy RNA conformers. Benchmarking on a set of RNAs with complex folds spanning up to 56 nucleotides in length yields structural models that recapitulate experimentally determined structures with all-heavy-atom RMSDs ranging from 2.4 to 6.5 Å. This platform represents an efficient approach for high-throughput RNA structure modeling and will facilitate analysis of diverse, newly discovered functional RNAs.
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Affiliation(s)
- Benfeard Williams
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Bo Zhao
- Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Arpit Tandon
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
| | - Kevin M Weeks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Qi Zhang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.,Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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45
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Schnieders R, Richter C, Warhaut S, de Jesus V, Keyhani S, Duchardt-Ferner E, Keller H, Wöhnert J, Kuhn LT, Breeze AL, Bermel W, Schwalbe H, Fürtig B. Evaluation of 15N-detected H-N correlation experiments on increasingly large RNAs. JOURNAL OF BIOMOLECULAR NMR 2017; 69:31-44. [PMID: 28879611 DOI: 10.1007/s10858-017-0132-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
Recently, 15N-detected multidimensional NMR experiments have been introduced for the investigation of proteins. Utilization of the slow transverse relaxation of nitrogen nuclei in a 15N-TROSY experiment allowed recording of high quality spectra for high molecular weight proteins, even in the absence of deuteration. Here, we demonstrate the applicability of three 15N-detected H-N correlation experiments (TROSY, BEST-TROSY and HSQC) to RNA. With the newly established 15N-detected BEST-TROSY experiment, which proves to be the most sensitive 15N-detected H-N correlation experiment, spectra for five RNA molecules ranging in size from 5 to 100 kDa were recorded. These spectra yielded high resolution in the 15N-dimension even for larger RNAs since the increase in line width with molecular weight is more pronounced in the 1H- than in the 15N-dimension. Further, we could experimentally validate the difference in relaxation behavior of imino groups in AU and GC base pairs. Additionally, we showed that 15N-detected experiments theoretically should benefit from sensitivity and resolution advantages at higher static fields but that the latter is obscured by exchange dynamics within the RNAs.
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Affiliation(s)
- Robbin Schnieders
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany
| | - Christian Richter
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany
| | - Sven Warhaut
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany
| | - Vanessa de Jesus
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany
| | - Sara Keyhani
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany
| | - Elke Duchardt-Ferner
- Institute for Molecular Biosciences, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt, Germany
| | - Heiko Keller
- Institute for Molecular Biosciences, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt, Germany
| | - Jens Wöhnert
- Institute for Molecular Biosciences, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt, Germany
| | - Lars T Kuhn
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Alexander L Breeze
- Astbury Centre for Structural Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Silberstreifen 4, 76287, Rheinstetten, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany.
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Str. 7, 60438, Frankfurt, Germany.
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46
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An excited state underlies gene regulation of a transcriptional riboswitch. Nat Chem Biol 2017; 13:968-974. [PMID: 28719589 PMCID: PMC5562522 DOI: 10.1038/nchembio.2427] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 05/22/2017] [Indexed: 11/08/2022]
Abstract
Riboswitches control gene expression through ligand-dependent structural rearrangements of the sensing aptamer domain. However, we found that the Bacillus cereus fluoride riboswitch aptamer adopts identical tertiary structures in solution with and without ligand. Using chemical-exchange saturation transfer (CEST) NMR spectroscopy, we revealed that the structured ligand-free aptamer transiently accesses a low-populated (∼1%) and short-lived (∼3 ms) excited conformational state that unravels a conserved 'linchpin' base pair to signal transcription termination. Upon fluoride binding, this highly localized, fleeting process is allosterically suppressed, which activates transcription. We demonstrated that this mechanism confers effective fluoride-dependent gene activation over a wide range of transcription rates, which is essential for robust toxicity responses across diverse cellular conditions. These results unveil a novel switching mechanism that employs ligand-dependent suppression of an aptamer excited state to coordinate regulatory conformational transitions rather than adopting distinct aptamer ground-state tertiary architectures, exemplifying a new mode of ligand-dependent RNA regulation.
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47
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Yuwen T, Kay LE. Longitudinal relaxation optimized amide 1H-CEST experiments for studying slow chemical exchange processes in fully protonated proteins. JOURNAL OF BIOMOLECULAR NMR 2017; 67:295-307. [PMID: 28357518 DOI: 10.1007/s10858-017-0104-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/06/2017] [Indexed: 06/06/2023]
Abstract
Chemical Exchange Saturation Transfer (CEST) experiments are increasingly used to study slow timescale exchange processes in biomolecules. Although 15N- and 13C-CEST have been the approaches of choice, the development of spin state selective 1H-CEST pulse sequences that separate the effects of chemical and dipolar exchange [T. Yuwen, A. Sekhar and L. E. Kay, Angew Chem Int Ed Engl 2016 doi: 10.1002/anie.201610759 (Yuwen et al. 2017)] significantly increases the utility of 1H-based experiments. Pulse schemes have been described previously for studies of highly deuterated proteins. We present here longitudinal-relaxation optimized amide 1H-CEST experiments for probing chemical exchange in protonated proteins. Applications involving a pair of proteins are presented establishing that accurate 1H chemical shifts of sparsely populated conformers can be obtained from simple analyses of 1H-CEST profiles. A discussion of the inherent differences between 15N-/13C- and 1H-CEST experiments is presented, leading to an optimal strategy for recording 1H-CEST experiments.
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Affiliation(s)
- Tairan Yuwen
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada.
- Hospital for Sick Children, Program in Molecular Structure and Function, Toronto, ON, Canada.
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48
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Vallurupalli P, Sekhar A, Yuwen T, Kay LE. Probing conformational dynamics in biomolecules via chemical exchange saturation transfer: a primer. JOURNAL OF BIOMOLECULAR NMR 2017; 67:243-271. [PMID: 28317074 DOI: 10.1007/s10858-017-0099-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 02/20/2017] [Indexed: 05/25/2023]
Abstract
Although Chemical Exchange Saturation Transfer (CEST) type NMR experiments have been used to study chemical exchange processes in molecules since the early 1960s, there has been renewed interest in the past several years in using this approach to study biomolecular conformational dynamics. The methodology is particularly powerful for the study of sparsely populated, transiently formed conformers that are recalcitrant to investigation using traditional biophysical tools, and it is complementary to relaxation dispersion and magnetization transfer experiments that have traditionally been used to study chemical exchange processes. Here we discuss the concepts behind the CEST experiment, focusing on practical aspects as well, we review some of the pulse sequences that have been developed to characterize protein and RNA conformational dynamics, and we discuss a number of examples where the CEST methodology has provided important insights into the role of dynamics in biomolecular function.
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Affiliation(s)
| | - Ashok Sekhar
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada
| | - Tairan Yuwen
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada.
- Hospital for Sick Children, Program in Molecular Structure and Function, Toronto, ON, Canada.
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49
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Juen MA, Wunderlich CH, Nußbaumer F, Tollinger M, Kontaxis G, Konrat R, Hansen DF, Kreutz C. Excited States of Nucleic Acids Probed by Proton Relaxation Dispersion NMR Spectroscopy. Angew Chem Int Ed Engl 2016; 55:12008-12. [PMID: 27533469 PMCID: PMC5082494 DOI: 10.1002/anie.201605870] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Indexed: 11/16/2022]
Abstract
In this work an improved stable isotope labeling protocol for nucleic acids is introduced. The novel building blocks eliminate/minimize homonuclear (13) C and (1) H scalar couplings thus allowing proton relaxation dispersion (RD) experiments to report accurately on the chemical exchange of nucleic acids. Using site-specific (2) H and (13) C labeling, spin topologies are introduced into DNA and RNA that make (1) H relaxation dispersion experiments applicable in a straightforward manner. The novel RNA/DNA building blocks were successfully incorporated into two nucleic acids. The A-site RNA was previously shown to undergo a two site exchange process in the micro- to millisecond time regime. Using proton relaxation dispersion experiments the exchange parameters determined earlier could be recapitulated, thus validating the proposed approach. We further investigated the dynamics of the cTAR DNA, a DNA transcript that is involved in the viral replication cycle of HIV-1. Again, an exchange process could be characterized and quantified. This shows the general applicablility of the novel labeling scheme for (1) H RD experiments of nucleic acids.
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Affiliation(s)
- Michael Andreas Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | | | - Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Martin Tollinger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Georg Kontaxis
- Computational Biology and Biomolecular NMR, Max F. Perutz Laboratories (MFPL), University of Vienna, Dr. Bohr Gasse 9 (VBC 5), 1030, Vienna, Austria
| | - Robert Konrat
- Computational Biology and Biomolecular NMR, Max F. Perutz Laboratories (MFPL), University of Vienna, Dr. Bohr Gasse 9 (VBC 5), 1030, Vienna, Austria
| | - D Flemming Hansen
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Darwin Building, Room 612, Gower Street, London, WC1E 6BT, UK.
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria.
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50
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Juen MA, Wunderlich CH, Nußbaumer F, Tollinger M, Kontaxis G, Konrat R, Hansen DF, Kreutz C. Excited States of Nucleic Acids Probed by Proton Relaxation Dispersion NMR Spectroscopy. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201605870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael Andreas Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI); University of Innsbruck; Innrain 80/82 6020 Innsbruck Austria
| | | | - Felix Nußbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI); University of Innsbruck; Innrain 80/82 6020 Innsbruck Austria
| | - Martin Tollinger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI); University of Innsbruck; Innrain 80/82 6020 Innsbruck Austria
| | - Georg Kontaxis
- Computational Biology and Biomolecular NMR; Max F. Perutz Laboratories (MFPL); University of Vienna; Dr. Bohr Gasse 9 (VBC 5) 1030 Vienna Austria
| | - Robert Konrat
- Computational Biology and Biomolecular NMR; Max F. Perutz Laboratories (MFPL); University of Vienna; Dr. Bohr Gasse 9 (VBC 5) 1030 Vienna Austria
| | - D. Flemming Hansen
- Institute of Structural and Molecular Biology; Division of Biosciences; University College London; Darwin Building, Room 612, Gower Street London WC1E 6BT UK
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI); University of Innsbruck; Innrain 80/82 6020 Innsbruck Austria
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