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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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2
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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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3
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Banijamali E, Baronti L, Becker W, Sajkowska-Kozielewicz JJ, Huang T, Palka C, Kosek D, Sweetapple L, Müller J, Stone MD, Andersson ER, Petzold K. RNA:RNA interaction in ternary complexes resolved by chemical probing. RNA (NEW YORK, N.Y.) 2023; 29:317-329. [PMID: 36617673 PMCID: PMC9945442 DOI: 10.1261/rna.079190.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
RNA regulation can be performed by a second targeting RNA molecule, such as in the microRNA regulation mechanism. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) probes the structure of RNA molecules and can resolve RNA:protein interactions, but RNA:RNA interactions have not yet been addressed with this technique. Here, we apply SHAPE to investigate RNA-mediated binding processes in RNA:RNA and RNA:RNA-RBP complexes. We use RNA:RNA binding by SHAPE (RABS) to investigate microRNA-34a (miR-34a) binding its mRNA target, the silent information regulator 1 (mSIRT1), both with and without the Argonaute protein, constituting the RNA-induced silencing complex (RISC). We show that the seed of the mRNA target must be bound to the microRNA loaded into RISC to enable further binding of the compensatory region by RISC, while the naked miR-34a is able to bind the compensatory region without seed interaction. The method presented here provides complementary structural evidence for the commonly performed luciferase-assay-based evaluation of microRNA binding-site efficiency and specificity on the mRNA target site and could therefore be used in conjunction with it. The method can be applied to any nucleic acid-mediated RNA- or RBP-binding process, such as splicing, antisense RNA binding, or regulation by RISC, providing important insight into the targeted RNA structure.
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Affiliation(s)
- Elnaz Banijamali
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Lorenzo Baronti
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Walter Becker
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | | | - Ting Huang
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Christina Palka
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
| | - David Kosek
- Department of Cell and Molecular Biology, Karolinska Institute, 17177 Stockholm, Sweden
| | - Lara Sweetapple
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Juliane Müller
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
| | - Michael D Stone
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
| | - Emma R Andersson
- Department of Cell and Molecular Biology, Karolinska Institute, 17177 Stockholm, Sweden
| | - Katja Petzold
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden
- Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch 7600, South Africa
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Dreydoppel M, Lichtenecker RJ, Akke M, Weininger U. 1H R 1ρ relaxation dispersion experiments in aromatic side chains. JOURNAL OF BIOMOLECULAR NMR 2021; 75:383-392. [PMID: 34510298 PMCID: PMC8642340 DOI: 10.1007/s10858-021-00382-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
Aromatic side chains are attractive probes of protein dynamic, since they are often key residues in enzyme active sites and protein binding sites. Dynamic processes on microsecond to millisecond timescales can be studied by relaxation dispersion experiments that attenuate conformational exchange contributions to the transverse relaxation rate by varying the refocusing frequency of applied radio-frequency fields implemented as either CPMG pulse trains or continuous spin-lock periods. Here we present an aromatic 1H R1ρ relaxation dispersion experiment enabling studies of two to three times faster exchange processes than achievable by existing experiments for aromatic side chains. We show that site-specific isotope labeling schemes generating isolated 1H-13C spin pairs with vicinal 2H-12C moieties are necessary to avoid anomalous relaxation dispersion profiles caused by Hartmann-Hahn matching due to the 3JHH couplings and limited chemical shift differences among 1H spins in phenylalanine, tyrosine and the six-ring moiety of tryptophan. This labeling pattern is sufficient in that remote protons do not cause additional complications. We validated the approach by measuring ring-flip kinetics in the small protein GB1. The determined rate constants, kflip, agree well with previous results from 13C R1ρ relaxation dispersion experiments, and yield 1H chemical shift differences between the two sides of the ring in good agreement with values measured under slow-exchange conditions. The aromatic1H R1ρ relaxation dispersion experiment in combination with the site-selective 1H-13C/2H-12C labeling scheme enable measurement of exchange rates up to kex = 2kflip = 80,000 s-1, and serve as a useful complement to previously developed 13C-based methods.
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Affiliation(s)
- Matthias Dreydoppel
- Institute of Physics, Biophysics, Martin-Luther-University Halle-Wittenberg, 06120, Halle (Saale), Germany
| | | | - Mikael Akke
- Division of Biophysical Chemistry, Center for Molecular Protein Science, Department of Chemistry, Lund University, P.O. Box 124, 22100, Lund, Sweden
| | - Ulrich Weininger
- Institute of Physics, Biophysics, Martin-Luther-University Halle-Wittenberg, 06120, Halle (Saale), Germany.
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Riad M, Hopkins N, Baronti L, Karlsson H, Schlagnitweit J, Petzold K. Mutate-and-chemical-shift-fingerprint (MCSF) to characterize excited states in RNA using NMR spectroscopy. Nat Protoc 2021; 16:5146-5170. [PMID: 34608336 DOI: 10.1038/s41596-021-00606-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 07/18/2021] [Indexed: 02/08/2023]
Abstract
It is important to understand the dynamics and higher energy structures of RNA, called excited states, to achieve better understanding of RNA function. R1ρ relaxation dispersion NMR spectroscopy (RD) determines chemical shift differences between the most stable, ground state and the short-lived, low-populated excited states. We describe a procedure for deducing the excited state structure from these chemical shift differences using the mutate-and-chemical-shift-fingerprint (MCSF) method, which requires ~2-6 weeks and moderate understanding of NMR and RNA structure. We recently applied the MCSF methodology to elucidate the excited state of microRNA 34a targeting the SIRT1 mRNA and use this example to demonstrate the analysis. The protocol comprises the following steps: (i) determination of the secondary structure of the excited state from RD chemical shift data, (ii) design of trapped excited state RNA, (iii) validation of the excited state structure by NMR, and (iv) MCSF analysis comparing the chemical shifts of the trapped excited state with the RD-derived chemical shift differences. MCSF enables observation of the short-lived RNA structures, which can be functionally and structurally characterized by entrapment.
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Affiliation(s)
- Magdalena Riad
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Noah Hopkins
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Lorenzo Baronti
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Hampus Karlsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Judith Schlagnitweit
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Katja Petzold
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
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6
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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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7
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Karlsson H, Feyrer H, Baronti L, Petzold K. Production of Structured RNA Fragments by In Vitro Transcription and HPLC Purification. Curr Protoc 2021; 1:e159. [PMID: 34138527 DOI: 10.1002/cpz1.159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The understanding of the functional importance of RNA has increased enormously in the last decades. This has required research on the RNA molecules themselves, with the concomitant need for obtaining purified RNA samples, such as for structural studies by NMR or other methods. The main method to create labeled and unlabeled RNA, T7 in vitro transcription, suffers from sequence-dependent yield and often low homogeneity for short constructs (<100 nt) and requires laborious purification. Additionally, the design of structured RNA fragments mimicking the structure of a larger biological RNA is often not straightforward. Secondary structure simulations can be used to make reliable predictions about the folding of a particular RNA fragment. In this article, we describe how to design an RNA construct of interest from a larger sequence, and we combine several previously published improvements of the in vitro transcription method, such as the use of 2'-methoxy modifications and dimethyl sulfoxide or the use of tandem repeats, to increase yield and purity of in vitro-transcribed RNA. Together with a high-performance liquid chromatography (HPLC) purification procedure using both reversed-phase ion-pairing and ion-exchange HPLC, we provide a robust protocol to obtain highly pure RNA of short to intermediate length in large quantities. The protocol optimizes yield, especially for RNA starting with nucleotides other than G. At the same time, it is simplified, and the required time is reduced. The protocols described here constitute a versatile pipeline for the production of purified RNA samples and are suitable for users with little experience in liquid chromatography. © 2021 The Authors. Basic Protocol 1: RNA construct design Basic Protocol 2: DNA template production and in vitro transcription Alternate Protocol: Tandem transcription and RNase H cleavage Basic Protocol 3: Reversed-phase ion-pairing HPLC purification Basic Protocol 4: Ion-exchange HPLC purification.
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Affiliation(s)
- Hampus Karlsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Hannes Feyrer
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Lorenzo Baronti
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.,Current address: Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Katja Petzold
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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8
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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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9
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Base-pair conformational switch modulates miR-34a targeting of Sirt1 mRNA. Nature 2020; 583:139-144. [PMID: 32461691 DOI: 10.1038/s41586-020-2336-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 03/12/2020] [Indexed: 11/08/2022]
Abstract
MicroRNAs (miRNAs) regulate the levels of translation of messenger RNAs (mRNAs). At present, the major parameter that can explain the selection of the target mRNA and the efficiency of translation repression is the base pairing between the 'seed' region of the miRNA and its counterpart mRNA1. Here we use R1ρ relaxation-dispersion nuclear magnetic resonance2 and molecular simulations3 to reveal a dynamic switch-based on the rearrangement of a single base pair in the miRNA-mRNA duplex-that elongates a weak five-base-pair seed to a complete seven-base-pair seed. This switch also causes coaxial stacking of the seed and supplementary helix fitting into human Argonaute 2 protein (Ago2), reminiscent of an active state in prokaryotic Ago4,5. Stabilizing this transient state leads to enhanced repression of the target mRNA in cells, revealing the importance of this miRNA-mRNA structure. Our observations tie together previous findings regarding the stepwise miRNA targeting process from an initial 'screening' state to an 'active' state, and unveil the role of the RNA duplex beyond the seed in Ago2.
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10
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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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11
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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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12
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Chu CC, Plangger R, Kreutz C, Al-Hashimi HM. Dynamic ensemble of HIV-1 RRE stem IIB reveals non-native conformations that disrupt the Rev-binding site. Nucleic Acids Res 2019; 47:7105-7117. [PMID: 31199872 PMCID: PMC6649712 DOI: 10.1093/nar/gkz498] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 05/21/2019] [Accepted: 06/07/2019] [Indexed: 01/01/2023] Open
Abstract
The HIV-1 Rev response element (RRE) RNA element mediates the nuclear export of intron containing viral RNAs by forming an oligomeric complex with the viral protein Rev. Stem IIB and nearby stem II three-way junction nucleate oligomerization through cooperative binding of two Rev molecules. Conformational flexibility at this RRE region has been shown to be important for Rev binding. However, the nature of the flexibility has remained elusive. Here, using NMR relaxation dispersion, including a new strategy for directly observing transient conformational states in large RNAs, we find that stem IIB alone or when part of the larger RREII three-way junction robustly exists in dynamic equilibrium with non-native excited state (ES) conformations that have a combined population of ∼20%. The ESs disrupt the Rev-binding site by changing local secondary structure, and their stabilization via point substitution mutations decreases the binding affinity to the Rev arginine-rich motif (ARM) by 15- to 80-fold. The ensemble clarifies the conformational flexibility observed in stem IIB, reveals long-range conformational coupling between stem IIB and the three-way junction that may play roles in cooperative Rev binding, and also identifies non-native RRE conformational states as new targets for the development of anti-HIV therapeutics.
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Affiliation(s)
- Chia-Chieh Chu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Raphael Plangger
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), Universität Innsbruck, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), Universität Innsbruck, 6020 Innsbruck, Austria
| | - 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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13
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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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14
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Schlagnitweit J, Steiner E, Karlsson H, Petzold K. Efficient Detection of Structure and Dynamics in Unlabeled RNAs: The SELOPE Approach. Chemistry 2018; 24:6067-6070. [PMID: 29504639 PMCID: PMC5947647 DOI: 10.1002/chem.201800992] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Indexed: 01/10/2023]
Abstract
The knowledge of structure and dynamics is crucial to explain the function of RNAs. While nuclear magnetic resonance (NMR) is well suited to probe these for complex biomolecules, it requires expensive, isotopically labeled samples, and long measurement times. Here we present SELOPE, a new robust, proton-only NMR method that allows us to obtain site-specific overview of structure and dynamics in an entire RNA molecule using an unlabeled sample. SELOPE simplifies assignment and allows for cost-effective screening of the response of nucleic acids to physiological changes (e.g. ion concentration) or screening of drugs in a high throughput fashion. This single technique allows us to probe an unprecedented range of exchange time scales (the whole μs to ms motion range) with increased sensitivity, surpassing all current experiments to detect chemical exchange. For the first time we could describe an RNA excited state using an unlabeled RNA.
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Affiliation(s)
- Judith Schlagnitweit
- Department of Medical Biochemistry and BiophysicsKarolinska Institute17177StockholmSweden
| | - Emilie Steiner
- Department of Medical Biochemistry and BiophysicsKarolinska Institute17177StockholmSweden
| | - Hampus Karlsson
- Department of Medical Biochemistry and BiophysicsKarolinska Institute17177StockholmSweden
| | - Katja Petzold
- Department of Medical Biochemistry and BiophysicsKarolinska Institute17177StockholmSweden
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15
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Clay MC, Ganser LR, Merriman DK, Al-Hashimi HM. Resolving sugar puckers in RNA excited states exposes slow modes of repuckering dynamics. Nucleic Acids Res 2017; 45:e134. [PMID: 28609788 PMCID: PMC5737546 DOI: 10.1093/nar/gkx525] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/01/2017] [Accepted: 06/05/2017] [Indexed: 11/15/2022] Open
Abstract
Recent studies have shown that RNAs exist in dynamic equilibrium with short-lived low-abundance 'excited states' that form by reshuffling base pairs in and around non-canonical motifs. These conformational states are proposed to be rich in non-canonical motifs and to play roles in the folding and regulatory functions of non-coding RNAs but their structure proves difficult to characterize given their transient nature. Here, we describe an approach for determining sugar pucker conformation in RNA excited states through nuclear magnetic resonance measurements of C1΄ and C4΄ rotating frame spin relaxation (R1ρ) in uniformly 13C/15N labeled RNA samples. Application to HIV-1 TAR exposed slow modes of sugar repuckering dynamics at the μs and ms timescale accompanying transitions between non-helical (C2΄-endo) to helical (C3΄-endo) conformations during formation of two distinct excited states. In contrast, we did not obtain any evidence for slow sugar repuckering dynamics for nucleotides in a variety of structural contexts that do not undergo non-helical to helical transitions. Our results outline a route for significantly improving the conformational characterization of RNA excited states and suggest that slow modes of repuckering dynamics gated by transient changes in secondary structure are quite common in RNA.
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Affiliation(s)
- Mary C. Clay
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Laura R. Ganser
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | | | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
- Department of Chemistry, Duke University, Durham, NC 27708, USA
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