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Roy R, Geng A, Shi H, Merriman DK, Dethoff EA, Salmon L, Al-Hashimi HM. Kinetic Resolution of the Atomic 3D Structures Formed by Ground and Excited Conformational States in an RNA Dynamic Ensemble. J Am Chem Soc 2023; 145:22964-22978. [PMID: 37831584 DOI: 10.1021/jacs.3c04614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Knowing the 3D structures formed by the various conformations populating the RNA free-energy landscape, their relative abundance, and kinetic interconversion rates is required to obtain a quantitative and predictive understanding of how RNAs fold and function at the atomic level. While methods integrating ensemble-averaged experimental data with computational modeling are helping define the most abundant conformations in RNA ensembles, elucidating their kinetic rates of interconversion and determining the 3D structures of sparsely populated short-lived RNA excited conformational states (ESs) remains challenging. Here, we developed an approach integrating Rosetta-FARFAR RNA structure prediction with NMR residual dipolar couplings and relaxation dispersion that simultaneously determines the 3D structures formed by the ground-state (GS) and ES subensembles, their relative abundance, and kinetic rates of interconversion. The approach is demonstrated on HIV-1 TAR, whose six-nucleotide apical loop was previously shown to form a sparsely populated (∼13%) short-lived (lifetime ∼ 45 μs) ES. In the GS, the apical loop forms a broad distribution of open conformations interconverting on the pico-to-nanosecond time scale. Most residues are unpaired and preorganized to bind the Tat-superelongation protein complex. The apical loop zips up in the ES, forming a narrow distribution of closed conformations, which sequester critical residues required for protein recognition. Our work introduces an approach for determining the 3D ensemble models formed by sparsely populated RNA conformational states, provides a rare atomic view of an RNA ES, and kinetically resolves the atomic 3D structures of RNA conformational substates, interchanging on time scales spanning 6 orders of magnitude, from picoseconds to microseconds.
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Affiliation(s)
- Rohit Roy
- Center for Genomic and Computational Biology, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Ainan Geng
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Dawn K Merriman
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Elizabeth A Dethoff
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Loïc Salmon
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, United States
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2
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Sannapureddi RKR, Mohanty MK, Salmon L, Sathyamoorthy B. Conformational Plasticity of Parallel G-Quadruplex─Implications on Duplex-Quadruplex Motifs. J Am Chem Soc 2023. [PMID: 37428641 DOI: 10.1021/jacs.3c03218] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
DNA G-quadruplexes are essential motifs in molecular biology performing a wide range of functions enabled by their unique and diverse structures. In this study, we focus on the conformational plasticity of the most abundant and biologically relevant parallel G-quadruplex topology. A multipronged approach of structure survey, solution-state NMR spectroscopy, and molecular dynamics simulations unravels subtle yet essential features of the parallel G-quadruplex topology. Stark differences in flexibility are observed for the nucleotides depending upon their positioning in the tetrad planes that are intricately correlated with the conformational sampling of the propeller loop. Importantly, the terminal nucleotides in the 5'-end versus the 3'-end of the parallel quadruplex display differential dynamics that manifests their ability to accommodate a duplex on either end of the G-quadruplex. The conformational plasticity characterized in this study provides essential cues toward biomolecular processes such as small molecular binding, intermolecular quadruplex stacking, and implications on how a duplex influences the structure of a neighboring quadruplex.
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Affiliation(s)
| | - Manish Kumar Mohanty
- Department of Chemistry, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Loïc Salmon
- Centre de RMN à Très Hauts Champs, UMR 5082 (CNRS, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1), University of Lyon, Villeurbanne 69100, France
| | - Bharathwaj Sathyamoorthy
- Department of Chemistry, Indian Institute of Science Education and Research, Bhopal 462066, India
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3
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Delhommel F, Martínez-Lumbreras S, Sattler M. Combining NMR, SAXS and SANS to characterize the structure and dynamics of protein complexes. Methods Enzymol 2022; 678:263-297. [PMID: 36641211 DOI: 10.1016/bs.mie.2022.09.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Understanding the structure and dynamics of biological macromolecules is essential to decipher the molecular mechanisms that underlie cellular functions. The description of structure and conformational dynamics often requires the integration of complementary techniques. In this review, we highlight the utility of combining nuclear magnetic resonance (NMR) spectroscopy with small angle scattering (SAS) to characterize these challenging biomolecular systems. NMR can assess the structure and conformational dynamics of multidomain proteins, RNAs and biomolecular complexes. It can efficiently provide information on interaction surfaces, long-distance restraints and relative domain orientations at residue-level resolution. Such information can be readily combined with high-resolution structural data available on subcomponents of biomolecular assemblies. Moreover, NMR is a powerful tool to characterize the dynamics of biomolecules on a wide range of timescales, from nanoseconds to seconds. On the other hand, SAS approaches provide global information on the size and shape of biomolecules and on the ensemble of all conformations present in solution. Therefore, NMR and SAS provide complementary data that are uniquely suited to investigate dynamic biomolecular assemblies. Here, we briefly review the type of data that can be obtained by both techniques and describe different approaches that can be used to combine them to characterize biomolecular assemblies. We then provide guidelines on which experiments are best suited depending on the type of system studied, ranging from fully rigid complexes, dynamic structures that interconvert between defined conformations and systems with very high structural heterogeneity.
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Affiliation(s)
- Florent Delhommel
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Santiago Martínez-Lumbreras
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching, Germany
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Garching, Germany.
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4
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Matoušková E, Dršata T, Pfeifferová L, Šponer J, Réblová K, Lankaš F. RNA kink-turns are highly anisotropic with respect to lateral displacement of the flanking stems. Biophys J 2022; 121:705-714. [PMID: 35122735 PMCID: PMC8943727 DOI: 10.1016/j.bpj.2022.01.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/23/2021] [Accepted: 01/28/2022] [Indexed: 11/02/2022] Open
Abstract
Kink-turns are highly bent internal loop motifs commonly found in the ribosome and other RNA complexes. They frequently act as binding sites for proteins and mediate tertiary interactions in larger RNA structures. Kink-turns have been a topic of intense research, but their elastic properties in the folded state are still poorly understood. Here we use extensive all-atom molecular dynamics simulations to parameterize a model of kink-turn in which the two flanking helical stems are represented by effective rigid bodies. Time series of the full set of six interhelical coordinates enable us to extract minimum energy shapes and harmonic stiffness constants for kink-turns from different RNA functional classes. The analysis suggests that kink-turns exhibit isotropic bending stiffness but are highly anisotropic with respect to lateral displacement of the stems. The most flexible lateral displacement mode is perpendicular to the plane of the static bend. These results may help understand the structural adaptation and mechanical signal transmission by kink-turns in complex natural and artificial RNA structures.
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Affiliation(s)
- Eva Matoušková
- Department of Informatics and Chemistry, University of Chemistry and Technology, Prague, Czech Republic
| | - Tomáš Dršata
- Department of Informatics and Chemistry, University of Chemistry and Technology, Prague, Czech Republic
| | - Lucie Pfeifferová
- Department of Informatics and Chemistry, University of Chemistry and Technology, Prague, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czech Republic
| | - Kamila Réblová
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Centre of Molecular Biology and Genetics, University Hospital Brno, Czech Republic.
| | - Filip Lankaš
- Department of Informatics and Chemistry, University of Chemistry and Technology, Prague, Czech Republic.
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5
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Binas O, de Jesus V, Landgraf T, Völklein AE, Martins J, Hymon D, Kaur Bains J, Berg H, Biedenbänder T, Fürtig B, Lakshmi Gande S, Niesteruk A, Oxenfarth A, Shahin Qureshi N, Schamber T, Schnieders R, Tröster A, Wacker A, Wirmer‐Bartoschek J, Wirtz Martin MA, Stirnal E, Azzaoui K, Richter C, Sreeramulu S, José Blommers MJ, Schwalbe H. 19 F NMR-Based Fragment Screening for 14 Different Biologically Active RNAs and 10 DNA and Protein Counter-Screens. Chembiochem 2021; 22:423-433. [PMID: 32794266 PMCID: PMC7436455 DOI: 10.1002/cbic.202000476] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/11/2020] [Indexed: 11/17/2022]
Abstract
We report here the nuclear magnetic resonance 19 F screening of 14 RNA targets with different secondary and tertiary structure to systematically assess the druggability of RNAs. Our RNA targets include representative bacterial riboswitches that naturally bind with nanomolar affinity and high specificity to cellular metabolites of low molecular weight. Based on counter-screens against five DNAs and five proteins, we can show that RNA can be specifically targeted. To demonstrate the quality of the initial fragment library that has been designed for easy follow-up chemistry, we further show how to increase binding affinity from an initial fragment hit by chemistry that links the identified fragment to the intercalator acridine. Thus, we achieve low-micromolar binding affinity without losing binding specificity between two different terminator structures.
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Affiliation(s)
- Oliver Binas
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Vanessa de Jesus
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Tom Landgraf
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Albrecht Eduard Völklein
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Jason Martins
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Daniel Hymon
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Jasleen Kaur Bains
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Hannes Berg
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Thomas Biedenbänder
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Boris Fürtig
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Santosh Lakshmi Gande
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Anna Niesteruk
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Andreas Oxenfarth
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Nusrat Shahin Qureshi
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Tatjana Schamber
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Robbin Schnieders
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Alix Tröster
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Anna Wacker
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Julia Wirmer‐Bartoschek
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Maria Alexandra Wirtz Martin
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Elke Stirnal
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Kamal Azzaoui
- Saverna TherapeuticsGewerbestrasse 244123AllschwilSwitzerland
| | - Christian Richter
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | - Sridhar Sreeramulu
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
| | | | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical BiologyCenter for Biomolecular Magnetic Resonance (BMRZ)Johann Wolfgang Goethe-University FrankfurtMax-von-Laue Strasse 760438Frankfurt am MainGermany
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6
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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: 6.2] [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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7
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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: 28] [Impact Index Per Article: 4.7] [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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8
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Bergonzo C, Grishaev A. Maximizing accuracy of RNA structure in refinement against residual dipolar couplings. JOURNAL OF BIOMOLECULAR NMR 2019; 73:117-139. [PMID: 31049778 DOI: 10.1007/s10858-019-00236-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 02/12/2019] [Indexed: 06/09/2023]
Abstract
Structural information about ribonucleic acid (RNA) is lagging behind that of proteins, in part due to its high charge and conformational variability. Molecular dynamics (MD) has played an important role in describing RNA structure, complementing information from both nuclear magnetic resonance (NMR), or X-ray crystallography. We examine the impact of the choice of the empirical force field for RNA structure refinement using cross-validation against residual dipolar couplings (RDCs) as structural accuracy reporter. Four force fields, representing both the state-of-the art in RNA simulation and the most popular selections in NMR structure determination, are compared for a prototypical A-RNA helix. RNA structural accuracy is also evaluated as a function of both density and nature of input NMR data including RDCs, anisotropic chemical shifts, and distance restraints. Our results show a complex interplay between the experimental restraints and the force fields indicating two best-performing choices: high-fidelity refinement in explicit solvent, and the conformational database-derived potentials. Accuracy of RNA models closely tracks the density of 1-bond C-H RDCs, with other data types having beneficial, but smaller effects. At lower RDC density, or when refining against NOEs only, the two selected force fields are capable of accurately describing RNA helices with little or no experimental RDC data, making them available for the higher order structure assembly or better quantification of the intramolecular dynamics. Unrestrained simulations of simple RNA motifs with state-of-the art MD force fields appear to capture the flexibility inherent in nucleic acids while also maintaining a good agreement with the experimental observables.
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Affiliation(s)
- Christina Bergonzo
- National Institute of Standards and Technology and Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD, 20850, USA
| | - Alexander Grishaev
- National Institute of Standards and Technology and Institute for Bioscience and Biotechnology Research, 9600 Gudelsky Drive, Rockville, MD, 20850, USA.
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9
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Merriman DK, Yuan J, Shi H, Majumdar A, Herschlag D, Al-Hashimi HM. Increasing the length of poly-pyrimidine bulges broadens RNA conformational ensembles with minimal impact on stacking energetics. RNA (NEW YORK, N.Y.) 2018; 24:1363-1376. [PMID: 30012568 PMCID: PMC6140463 DOI: 10.1261/rna.066258.118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 07/05/2018] [Indexed: 05/03/2023]
Abstract
Helical elements separated by bulges frequently undergo transitions between unstacked and coaxially stacked conformations during the folding and function of noncoding RNAs. Here, we examine the dynamic properties of poly-pyrimidine bulges of varying length (n = 1-4, 7) across a range of Mg2+ concentrations using HIV-1 TAR RNA as a model system and solution NMR spectroscopy. In the absence of Mg2+, helices linked by bulges with n ≥ 3 residues adopt predominantly unstacked conformations (stacked population <15%), whereas one-bulge and two-bulge motifs adopt predominantly stacked conformations (stacked population >74%). In the presence of 3 mM Mg2+, the helices predominantly coaxially stack (stacked population >84%), regardless of bulge length, and the midpoint for the Mg2+-dependent stacking transition is within threefold regardless of bulge length. In the absence of Mg2+, the difference between free energy of interhelical coaxial stacking across the bulge variants is estimated to be ∼2.9 kcal/mol, based on an NMR chemical shift mapping with stacking being more energetically disfavored for the longer bulges. This difference decreases to ∼0.4 kcal/mol in the presence of Mg2+ NMR RDCs and resonance intensity data show increased dynamics in the stacked state with increasing bulge length in the presence of Mg2+ We propose that Mg2+ helps to neutralize the growing electrostatic repulsion in the stacked state with increasing bulge length thereby increasing the number of coaxial conformations that are sampled. Energetically compensated interhelical stacking dynamics may help to maximize the conformational adaptability of RNA and allow a wide range of conformations to be optimally stabilized by proteins and ligands.
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Affiliation(s)
- Dawn K Merriman
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Jiayi Yuan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Biology, Duke University, Durham, North Carolina 27708, USA
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Ananya Majumdar
- Biomolecular NMR Facility, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Hashim M Al-Hashimi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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10
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Nichols PJ, Born A, Henen MA, Strotz D, Celestine CN, Güntert P, Vögeli B. Extending the Applicability of Exact Nuclear Overhauser Enhancements to Large Proteins and RNA. Chembiochem 2018; 19:1695-1701. [PMID: 29883016 DOI: 10.1002/cbic.201800237] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Indexed: 01/24/2023]
Abstract
Distance-dependent nuclear Overhauser enhancements (NOEs) are one of the most popular and important experimental restraints for calculating NMR structures. Despite this, they are mostly employed as semiquantitative upper distance bounds, and this discards the wealth of information that is encoded in the cross-relaxation rate constant. Information that is lost includes exact distances between protons and dynamics that occur on the sub-millisecond timescale. Our recently introduced exact measurement of the NOE (eNOE) requires little additional experimental effort relative to other NMR observables. So far, we have used eNOEs to calculate multistate ensembles of proteins up to approximately 150 residues. Here, we briefly revisit eNOE methodology and present two new directions for the use of eNOEs: applications to large proteins and RNA.
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Affiliation(s)
- Parker J Nichols
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO, 80045, USA
| | - Alexandra Born
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO, 80045, USA
| | - Morkos A Henen
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO, 80045, USA
- Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Dean Strotz
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
| | - Chi N Celestine
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, 75123, Uppsala, Sweden
| | - Peter Güntert
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
- Institute of Biophysical Chemistry, Goethe Universität Frankfurt, Max-von-Laue-Strasse 9, 60438, Frankfurt am Main, Germany
- Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo, 192-0397, Japan
| | - Beat Vögeli
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO, 80045, USA
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11
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Marchant J, Bax A, Summers MF. Accurate Measurement of Residual Dipolar Couplings in Large RNAs by Variable Flip Angle NMR. J Am Chem Soc 2018; 140:6978-6983. [PMID: 29757635 PMCID: PMC6021016 DOI: 10.1021/jacs.8b03298] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
NMR approaches using nucleotide-specific deuterium labeling schemes have enabled structural studies of biologically relevant RNAs of increasing size and complexity. Although local structure is well-determined using these methods, definition of global structural features, including relative orientations of independent helices, remains a challenge. Residual dipolar couplings, a potential source of orientation information, have not been obtainable for large RNAs due to poor sensitivity resulting from rapid heteronuclear signal decay. Here we report a novel multiple quantum NMR method for RDC determination that employs flip angle variation rather than a coupling evolution period. The accuracy of the method and its utility for establishing interhelical orientations are demonstrated for a 36-nucleotide RNA, for which comparative data could be obtained. Applied to a 78 kDa Rev response element from the HIV-1 virus, which has an effective rotational correlation time of ca. 160 ns, the method yields sensitivity gains of an order of magnitude or greater over existing approaches. Solution-state access to structural organization in RNAs of at least 230 nucleotides is now possible.
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Affiliation(s)
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes, Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892 , United States
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12
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Grytz CM, Kazemi S, Marko A, Cekan P, Güntert P, Sigurdsson ST, Prisner TF. Determination of helix orientations in a flexible DNA by multi-frequency EPR spectroscopy. Phys Chem Chem Phys 2018; 19:29801-29811. [PMID: 29090294 DOI: 10.1039/c7cp04997h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Distance measurements are performed between a pair of spin labels attached to nucleic acids using Pulsed Electron-Electron Double Resonance (PELDOR, also called DEER) spectroscopy which is a complementary tool to other structure determination methods in structural biology. The rigid spin label Ç, when incorporated pairwise into two helical parts of a nucleic acid molecule, allows the determination of both the mutual orientation and the distance between those labels, since Ç moves rigidly with the helix to which it is attached. We have developed a two-step protocol to investigate the conformational flexibility of flexible nucleic acid molecules by multi-frequency PELDOR. In the first step, a library with a broad collection of conformers, which are in agreement with topological constraints, NMR restraints and distances derived from PELDOR, was created. In the second step, a weighted structural ensemble of these conformers was chosen, such that it fits the multi-frequency PELDOR time traces of all doubly Ç-labelled samples simultaneously. This ensemble reflects the global structure and the conformational flexibility of the two-way DNA junction. We demonstrate this approach on a flexible bent DNA molecule, consisting of two short helical parts with a five adenine bulge at the center. The kink and twist motions between both helical parts were quantitatively determined and showed high flexibility, in agreement with a Förster Resonance Energy Transfer (FRET) study on a similar bent DNA motif. The approach presented here should be useful to describe the relative orientation of helical motifs and the conformational flexibility of nucleic acid structures, both alone and in complexes with proteins and other molecules.
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Affiliation(s)
- C M Grytz
- Institute of Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany.
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13
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Dršata T, Réblová K, Beššeová I, Šponer J, Lankaš F. rRNA C-Loops: Mechanical Properties of a Recurrent Structural Motif. J Chem Theory Comput 2017; 13:3359-3371. [DOI: 10.1021/acs.jctc.7b00061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tomáš Dršata
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague, Czech Republic
- Institute
of Biophysics, Academy of Sciences of the Czech Republic, Královopolská
135, 612 65 Brno, Czech Republic
| | - Kamila Réblová
- CEITEC—Central European Institute of Technology, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
| | - Ivana Beššeová
- Institute
of Biophysics, Academy of Sciences of the Czech Republic, Královopolská
135, 612 65 Brno, Czech Republic
| | - Jiří Šponer
- Institute
of Biophysics, Academy of Sciences of the Czech Republic, Královopolská
135, 612 65 Brno, Czech Republic
- CEITEC—Central European Institute of Technology, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
| | - Filip Lankaš
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague, Czech Republic
- Laboratory
of Informatics and Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
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14
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Structural conservation in the template/pseudoknot domain of vertebrate telomerase RNA from teleost fish to human. Proc Natl Acad Sci U S A 2016; 113:E5125-34. [PMID: 27531956 DOI: 10.1073/pnas.1607411113] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Telomerase is an RNA-protein complex that includes a unique reverse transcriptase that catalyzes the addition of single-stranded telomere DNA repeats onto the 3' ends of linear chromosomes using an integral telomerase RNA (TR) template. Vertebrate TR contains the template/pseudoknot (t/PK) and CR4/5 domains required for telomerase activity in vitro. All vertebrate pseudoknots include two subdomains: P2ab (helices P2a and P2b with a 5/6-nt internal loop) and the minimal pseudoknot (P2b-P3 and associated loops). A helical extension of P2a, P2a.1, is specific to mammalian TR. Using NMR, we investigated the structures of the full-length TR pseudoknot and isolated subdomains in Oryzias latipes (Japanese medaka fish), which has the smallest vertebrate TR identified to date. We determined the solution NMR structure and studied the dynamics of medaka P2ab, and identified all base pairs and tertiary interactions in the minimal pseudoknot. Despite differences in length and sequence, the structure of medaka P2ab is more similar to human P2ab than predicted, and the medaka minimal pseudoknot has the same tertiary interactions as the human pseudoknot. Significantly, although P2a.1 is not predicted to form in teleost fish, we find that it forms in the full-length pseudoknot via an unexpected hairpin. Model structures of the subdomains are combined to generate a model of t/PK. These results provide evidence that the architecture for the vertebrate t/PK is conserved from teleost fish to human. The organization of the t/PK on telomerase reverse transcriptase for medaka and human is modeled based on the cryoEM structure of Tetrahymena telomerase, providing insight into function.
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15
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Merriman DK, Xue Y, Yang S, Kimsey IJ, Shakya A, Clay M, Al-Hashimi HM. Shortening the HIV-1 TAR RNA Bulge by a Single Nucleotide Preserves Motional Modes over a Broad Range of Time Scales. Biochemistry 2016; 55:4445-56. [PMID: 27232530 DOI: 10.1021/acs.biochem.6b00285] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Helix-junction-helix (HJH) motifs are flexible building blocks of RNA architecture that help define the orientation and dynamics of helical domains. They are also frequently involved in adaptive recognition of proteins and small molecules and in the formation of tertiary contacts. Here, we use a battery of nuclear magnetic resonance techniques to examine how deleting a single bulge residue (C24) from the human immunodeficiency virus type 1 (HIV-1) transactivation response element (TAR) trinucleotide bulge (U23-C24-U25) affects dynamics over a broad range of time scales. Shortening the bulge has an effect on picosecond-to-nanosecond interhelical and local bulge dynamics similar to that casued by increasing the Mg(2+) and Na(+) concentration, whereby a preexisting two-state equilibrium in TAR is shifted away from a bent flexible conformation toward a coaxial conformation, in which all three bulge residues are flipped out and flexible. Surprisingly, the point deletion minimally affects microsecond-to-millisecond conformational exchange directed toward two low-populated and short-lived excited conformational states that form through reshuffling of bases pairs throughout TAR. The mutant does, however, adopt a slightly different excited conformational state on the millisecond time scale, in which U23 is intrahelical, mimicking the expected conformation of residue C24 in the excited conformational state of wild-type TAR. Thus, minor changes in HJH topology preserve motional modes in RNA occurring over the picosecond-to-millisecond time scales but alter the relative populations of the sampled states or cause subtle changes in their conformational features.
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Affiliation(s)
- Dawn K Merriman
- Department of Chemistry, Duke University , Durham, North Carolina 27708, United States
| | - Yi Xue
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Shan Yang
- Baxter Health Care (Suzhou) Company, Ltd. , Suzhou, Jiang Su 215028, China
| | - Isaac J Kimsey
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Anisha Shakya
- Department of Chemistry and Biophysics, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Mary Clay
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Hashim M Al-Hashimi
- Department of Chemistry, Duke University , Durham, North Carolina 27708, United States.,Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
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16
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Zhao B, Zhang Q. Measuring Residual Dipolar Couplings in Excited Conformational States of Nucleic Acids by CEST NMR Spectroscopy. J Am Chem Soc 2015; 137:13480-3. [PMID: 26462068 DOI: 10.1021/jacs.5b09014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nucleic acids undergo structural transitions to access sparsely populated and transiently lived conformational states--or excited conformational states--that play important roles in diverse biological processes. Despite ever-increasing detection of these functionally essential states, 3D structure determination of excited states (ESs) of RNA remains elusive. This is largely due to challenges in obtaining high-resolution structural constraints in these ESs by conventional structural biology approaches. Here, we present nucleic-acid-optimized chemical exchange saturation transfer (CEST) NMR spectroscopy for measuring residual dipolar couplings (RDCs), which provide unique long-range angular constraints in ESs of nucleic acids. We demonstrate these approaches on a fluoride riboswitch, where one-bond (13)C-(1)H RDCs from both base and sugar moieties provide direct structural probes into an ES of the ligand-free riboswitch.
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Affiliation(s)
- Bo Zhao
- Department of Biochemistry and Biophysics and ‡Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Qi Zhang
- Department of Biochemistry and Biophysics and ‡Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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17
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Zhou H, Hintze BJ, Kimsey IJ, Sathyamoorthy B, Yang S, Richardson JS, Al-Hashimi HM. New insights into Hoogsteen base pairs in DNA duplexes from a structure-based survey. Nucleic Acids Res 2015; 43:3420-33. [PMID: 25813047 PMCID: PMC4402545 DOI: 10.1093/nar/gkv241] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/01/2015] [Indexed: 11/14/2022] Open
Abstract
Hoogsteen (HG) base pairs (bps) provide an alternative pairing geometry to Watson-Crick (WC) bps and can play unique functional roles in duplex DNA. Here, we use structural features unique to HG bps (syn purine base, HG hydrogen bonds and constricted C1'-C1' distance across the bp) to search for HG bps in X-ray structures of DNA duplexes in the Protein Data Bank. The survey identifies 106 A•T and 34 G•C HG bps in DNA duplexes, many of which are undocumented in the literature. It also uncovers HG-like bps with syn purines lacking HG hydrogen bonds or constricted C1'-C1' distances that are analogous to conformations that have been proposed to populate the WC-to-HG transition pathway. The survey reveals HG preferences similar to those observed for transient HG bps in solution by nuclear magnetic resonance, including stronger preferences for A•T versus G•C bps, TA versus GG steps, and also suggests enrichment at terminal ends with a preference for 5'-purine. HG bps induce small local perturbations in neighboring bps and, surprisingly, a small but significant degree of DNA bending (∼14°) directed toward the major groove. The survey provides insights into the preferences and structural consequences of HG bps in duplex DNA.
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Affiliation(s)
- Huiqing Zhou
- Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | - Bradley J Hintze
- Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | - Isaac J Kimsey
- Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | | | - Shan Yang
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | | | - Hashim M Al-Hashimi
- Department of Biochemistry, Duke University, Durham, NC 27710, USA Department of Chemistry, Duke University, Durham, NC 27708, USA
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18
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Mouzakis KD, Dethoff EA, Tonelli M, Al-Hashimi H, Butcher SE. Dynamic motions of the HIV-1 frameshift site RNA. Biophys J 2015; 108:644-54. [PMID: 25650931 PMCID: PMC4317556 DOI: 10.1016/j.bpj.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 11/11/2014] [Accepted: 12/05/2014] [Indexed: 12/13/2022] Open
Abstract
The HIV-1 frameshift site (FS) plays a critical role in viral replication. During translation, the HIV-1 FS transitions from a 3-helix to a 2-helix junction RNA secondary structure. The 2-helix junction structure contains a GGA bulge, and purine-rich bulges are common motifs in RNA secondary structure. Here, we investigate the dynamics of the HIV-1 FS 2-helix junction RNA. Interhelical motions were studied under different ionic conditions using NMR order tensor analysis of residual dipolar couplings. In 150 mM potassium, the RNA adopts a 43°(±4°) interhelical bend angle (β) and displays large amplitude, anisotropic interhelical motions characterized by a 0.52(±0.04) internal generalized degree of order (GDOint) and distinct order tensor asymmetries for its two helices (η = 0.26(±0.04) and 0.5(±0.1)). These motions are effectively quenched by addition of 2 mM magnesium (GDOint = 0.87(±0.06)), which promotes a near-coaxial conformation (β = 15°(±6°)) of the two helices. Base stacking in the bulge was investigated using the fluorescent purine analog 2-aminopurine. These results indicate that magnesium stabilizes extrahelical conformations of the bulge nucleotides, thereby promoting coaxial stacking of helices. These results are highly similar to previous studies of the HIV transactivation response RNA, despite a complete lack of sequence similarity between the two RNAs. Thus, the conformational space of these RNAs is largely determined by the topology of their interhelical junctions.
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Affiliation(s)
- Kathryn D Mouzakis
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Elizabeth A Dethoff
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina
| | - Marco Tonelli
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | | | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin.
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19
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Eichhorn CD, Al-Hashimi HM. Structural dynamics of a single-stranded RNA-helix junction using NMR. RNA (NEW YORK, N.Y.) 2014; 20:782-91. [PMID: 24742933 PMCID: PMC4024633 DOI: 10.1261/rna.043711.113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Many regulatory RNAs contain long single strands (ssRNA) that adjoin secondary structural elements. Here, we use NMR spectroscopy to study the dynamic properties of a 12-nucleotide (nt) ssRNA tail derived from the prequeuosine riboswitch linked to the 3' end of a 48-nt hairpin. Analysis of chemical shifts, NOE connectivity, (13)C spin relaxation, and residual dipolar coupling data suggests that the first two residues (A25 and U26) in the ssRNA tail stack onto the adjacent helix and assume an ordered conformation. The following U26-A27 step marks the beginning of an A6-tract and forms an acute pivot point for substantial motions within the tail, which increase toward the terminal end. Despite substantial internal motions, the ssRNA tail adopts, on average, an A-form helical conformation that is coaxial with the helix. Our results reveal a surprising degree of structural and dynamic complexity at the ssRNA-helix junction, which involves a fine balance between order and disorder that may facilitate efficient pseudoknot formation on ligand recognition.
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Affiliation(s)
- Catherine D. Eichhorn
- Chemical Biology Doctoral Program, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
- Corresponding authorE-mail
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20
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From a structural average to the conformational ensemble of a DNA bulge. Proc Natl Acad Sci U S A 2014; 111:E1473-80. [PMID: 24706812 DOI: 10.1073/pnas.1317032111] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Direct experimental measurements of conformational ensembles are critical for understanding macromolecular function, but traditional biophysical methods do not directly report the solution ensemble of a macromolecule. Small-angle X-ray scattering interferometry has the potential to overcome this limitation by providing the instantaneous distance distribution between pairs of gold-nanocrystal probes conjugated to a macromolecule in solution. Our X-ray interferometry experiments reveal an increasing bend angle of DNA duplexes with bulges of one, three, and five adenosine residues, consistent with previous FRET measurements, and further reveal an increasingly broad conformational ensemble with increasing bulge length. The distance distributions for the AAA bulge duplex (3A-DNA) with six different Au-Au pairs provide strong evidence against a simple elastic model in which fluctuations occur about a single conformational state. Instead, the measured distance distributions suggest a 3A-DNA ensemble with multiple conformational states predominantly across a region of conformational space with bend angles between 24 and 85 degrees and characteristic bend directions and helical twists and displacements. Additional X-ray interferometry experiments revealed perturbations to the ensemble from changes in ionic conditions and the bulge sequence, effects that can be understood in terms of electrostatic and stacking contributions to the ensemble and that demonstrate the sensitivity of X-ray interferometry. Combining X-ray interferometry ensemble data with molecular dynamics simulations gave atomic-level models of representative conformational states and of the molecular interactions that may shape the ensemble, and fluorescence measurements with 2-aminopurine-substituted 3A-DNA provided initial tests of these atomistic models. More generally, X-ray interferometry will provide powerful benchmarks for testing and developing computational methods.
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21
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Abstract
RNA dynamics play a fundamental role in many cellular functions. However, there is no general framework to describe these complex processes, which typically consist of many structural maneuvers that occur over timescales ranging from picoseconds to seconds. Here, we classify RNA dynamics into distinct modes representing transitions between basins on a hierarchical free-energy landscape. These transitions include large-scale secondary-structural transitions at >0.1-s timescales, base-pair/tertiary dynamics at microsecond-to-millisecond timescales, stacking dynamics at timescales ranging from nanoseconds to microseconds, and other "jittering" motions at timescales ranging from picoseconds to nanoseconds. We review various modes within these three different tiers, the different mechanisms by which they are used to regulate function, and how they can be coupled together to achieve greater functional complexity.
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22
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Mustoe AM, Al-Hashimi HM, Brooks CL. Coarse grained models reveal essential contributions of topological constraints to the conformational free energy of RNA bulges. J Phys Chem B 2014; 118:2615-27. [PMID: 24547945 PMCID: PMC3983386 DOI: 10.1021/jp411478x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
![]()
Recent studies have shown that simple
stereochemical constraints
encoded at the RNA secondary structure level significantly restrict
the orientation of RNA helices across two-way junctions and yield
physically reasonable distributions of RNA 3D conformations. Here
we develop a new coarse-grain model, TOPRNA, that is optimized for
exploring detailed aspects of these topological constraints in complex
RNA systems. Unlike prior models, TOPRNA effectively treats RNAs as
collections of semirigid helices linked by freely rotatable single
strands, allowing us to isolate the effects of secondary structure
connectivity and sterics on 3D structure. Simulations of bulge junctions
show that TOPRNA captures new aspects of topological constraints,
including variations arising from deviations in local A-form structure,
translational displacements of the helices, and stereochemical constraints
imposed by bulge-linker nucleotides. Notably, these aspects of topological
constraints define free energy landscapes that coincide with the distribution
of bulge conformations in the PDB. Our simulations also quantitatively
reproduce NMR RDC measurements made on HIV-1 TAR at low salt concentrations,
although not for different TAR mutants or at high salt concentrations.
Our results confirm that topological constraints are an important
determinant of bulge conformation and dynamics and demonstrate the
utility of TOPRNA for studying the topological constraints of complex
RNAs.
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Affiliation(s)
- Anthony M Mustoe
- Departments of Biophysics and ‡Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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23
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Structural determinants for ligand capture by a class II preQ1 riboswitch. Proc Natl Acad Sci U S A 2014; 111:E663-71. [PMID: 24469808 DOI: 10.1073/pnas.1400126111] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Prequeuosine (preQ1) riboswitches are RNA regulatory elements located in the 5' UTR of genes involved in the biosynthesis and transport of preQ1, a precursor of the modified base queuosine universally found in four tRNAs. The preQ1 class II (preQ1-II) riboswitch regulates preQ1 biosynthesis at the translational level. We present the solution NMR structure and conformational dynamics of the 59 nucleotide Streptococcus pneumoniae preQ1-II riboswitch bound to preQ1. Unlike in the preQ1 class I (preQ1-I) riboswitch, divalent cations are required for high-affinity binding. The solution structure is an unusual H-type pseudoknot featuring a P4 hairpin embedded in loop 3, which forms a three-way junction with the other two stems. (13)C relaxation and residual dipolar coupling experiments revealed interhelical flexibility of P4. We found that the P4 helix and flanking adenine residues play crucial and unexpected roles in controlling pseudoknot formation and, in turn, sequestering the Shine-Dalgarno sequence. Aided by divalent cations, P4 is poised to act as a "screw cap" on preQ1 recognition to block ligand exit and stabilize the binding pocket. Comparison of preQ1-I and preQ1-II riboswitch structures reveals that whereas both form H-type pseudoknots and recognize preQ1 using one A, C, or U nucleotide from each of three loops, these nucleotides interact with preQ1 differently, with preQ1 inserting into different grooves. Our studies show that the preQ1-II riboswitch uses an unusual mechanism to harness exquisite control over queuosine metabolism.
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24
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Shen K, Wang Y, Hwang Fu YH, Zhang Q, Feigon J, Shan SO. Molecular mechanism of GTPase activation at the signal recognition particle (SRP) RNA distal end. J Biol Chem 2013; 288:36385-97. [PMID: 24151069 DOI: 10.1074/jbc.m113.513614] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The signal recognition particle (SRP) RNA is a universally conserved and essential component of the SRP that mediates the co-translational targeting of proteins to the correct cellular membrane. During the targeting reaction, two functional ends in the SRP RNA mediate distinct functions. Whereas the RNA tetraloop facilitates initial assembly of two GTPases between the SRP and SRP receptor, this GTPase complex subsequently relocalizes ∼100 Å to the 5',3'-distal end of the RNA, a conformation crucial for GTPase activation and cargo handover. Here we combined biochemical, single molecule, and NMR studies to investigate the molecular mechanism of this large scale conformational change. We show that two independent sites contribute to the interaction of the GTPase complex with the SRP RNA distal end. Loop E plays a crucial role in the precise positioning of the GTPase complex on these two sites by inducing a defined bend in the RNA helix and thus generating a preorganized recognition surface. GTPase docking can be uncoupled from its subsequent activation, which is mediated by conserved bases in the next internal loop. These results, combined with recent structural work, elucidate how the SRP RNA induces GTPase relocalization and activation at the end of the protein targeting reaction.
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Affiliation(s)
- Kuang Shen
- From the Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 and
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25
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Schmidt C, Irausquin SJ, Valafar H. Advances in the REDCAT software package. BMC Bioinformatics 2013; 14:302. [PMID: 24098943 PMCID: PMC3840585 DOI: 10.1186/1471-2105-14-302] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 09/13/2013] [Indexed: 12/24/2022] Open
Abstract
Background Residual Dipolar Couplings (RDCs) have emerged in the past two decades as an informative source of experimental restraints for the study of structure and dynamics of biological macromolecules and complexes. The REDCAT software package was previously introduced for the analysis of molecular structures using RDC data. Here we report additional features that have been included in this software package in order to expand the scope of its analyses. We first discuss the features that enhance REDCATs user-friendly nature, such as the integration of a number of analyses into one single operation and enabling convenient examination of a structural ensemble in order to identify the most suitable structure. We then describe the new features which expand the scope of RDC analyses, performing exercises that utilize both synthetic and experimental data to illustrate and evaluate different features with regard to structure refinement and structure validation. Results We establish the seamless interaction that takes place between REDCAT, VMD, and Xplor-NIH in demonstrations that utilize our newly developed REDCAT-VMD and XplorGUI interfaces. These modules enable visualization of RDC analysis results on the molecular structure displayed in VMD and refinement of structures with Xplor-NIH, respectively. We also highlight REDCAT’s Error-Analysis feature in reporting the localized fitness of a structure to RDC data, which provides a more effective means of recognizing local structural anomalies. This allows for structurally sound regions of a molecule to be identified, and for any refinement efforts to be focused solely on locally distorted regions. Conclusions The newly engineered REDCAT software package, which is available for download via the WWW from http://ifestos.cse.sc.edu, has been developed in the Object Oriented C++ environment. Our most recent enhancements to REDCAT serve to provide a more complete RDC analysis suite, while also accommodating a more user-friendly experience, and will be of great interest to the community of researchers and developers since it hides the complications of software development.
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Affiliation(s)
- Chris Schmidt
- Department of Computer Science & Engineering, University of South Carolina, Columbia, SC 29208, USA.
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26
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Protein structure validation and identification from unassigned residual dipolar coupling data using 2D-PDPA. Molecules 2013; 18:10162-88. [PMID: 23973992 PMCID: PMC4090686 DOI: 10.3390/molecules180910162] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/10/2013] [Accepted: 08/13/2013] [Indexed: 11/22/2022] Open
Abstract
More than 90% of protein structures submitted to the PDB each year are homologous to some previously characterized protein structure. The extensive resources that are required for structural characterization of proteins can be justified for the 10% of the novel structures, but not for the remaining 90%. This report presents the 2D-PDPA method, which utilizes unassigned residual dipolar coupling in order to address the economics of structure determination of routine proteins by reducing the data acquisition and processing time. 2D-PDPA has been demonstrated to successfully identify the correct structure of an array of proteins that range from 46 to 445 residues in size from a library of 619 decoy structures by using unassigned simulated RDC data. When using experimental data, 2D-PDPA successfully identified the correct NMR structures from the same library of decoy structures. In addition, the most homologous X-ray structure was also identified as the second best structural candidate. Finally, success of 2D-PDPA in identifying and evaluating the most appropriate structure from a set of computationally predicted structures in the case of a previously uncharacterized protein Pf2048.1 has been demonstrated. This protein exhibits less than 20% sequence identity to any protein with known structure and therefore presents a compelling and practical application of our proposed work.
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27
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van der Werf RM, Tessari M, Wijmenga SS. Nucleic acid helix structure determination from NMR proton chemical shifts. JOURNAL OF BIOMOLECULAR NMR 2013; 56:95-112. [PMID: 23564038 DOI: 10.1007/s10858-013-9725-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 03/27/2013] [Indexed: 05/12/2023]
Abstract
We present a method for de novo derivation of the three-dimensional helix structure of nucleic acids using non-exchangeable proton chemical shifts as sole source of experimental restraints. The method is called chemical shift de novo structure derivation protocol employing singular value decomposition (CHEOPS) and uses iterative singular value decomposition to optimize the structure in helix parameter space. The correct performance of CHEOPS and its range of application are established via an extensive set of structure derivations using either simulated or experimental chemical shifts as input. The simulated input data are used to assess in a defined manner the effect of errors or limitations in the input data on the derived structures. We find that the RNA helix parameters can be determined with high accuracy. We finally demonstrate via three deposited RNA structures that experimental proton chemical shifts suffice to derive RNA helix structures with high precision and accuracy. CHEOPS provides, subject to further development, new directions for high-resolution NMR structure determination of nucleic acids.
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Affiliation(s)
- Ramon M van der Werf
- Department of Biophysical Chemistry, Institute of Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Réblová K, Šponer J, Lankaš F. Structure and mechanical properties of the ribosomal L1 stalk three-way junction. Nucleic Acids Res 2012; 40:6290-303. [PMID: 22451682 PMCID: PMC3401443 DOI: 10.1093/nar/gks258] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/07/2012] [Accepted: 03/07/2012] [Indexed: 01/06/2023] Open
Abstract
The L1 stalk is a key mobile element of the large ribosomal subunit which interacts with tRNA during translocation. Here, we investigate the structure and mechanical properties of the rRNA H76/H75/H79 three-way junction at the base of the L1 stalk from four different prokaryotic organisms. We propose a coarse-grained elastic model and parameterize it using large-scale atomistic molecular dynamics simulations. Global properties of the junction are well described by a model in which the H76 helix is represented by a straight, isotropically flexible elastic rod, while the junction core is represented by an isotropically flexible spherical hinge. Both the core and the helix contribute substantially to the overall H76 bending fluctuations. The presence of wobble pairs in H76 does not induce any increased flexibility or anisotropy to the helix. The half-closed conformation of the L1 stalk seems to be accessible by thermal fluctuations of the junction itself, without any long-range allosteric effects. Bending fluctuations of H76 with a bulge introduced in it suggest a rationale for the precise position of the bulge in eukaryotes. Our elastic model can be generalized to other RNA junctions found in biological systems or in nanotechnology.
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Affiliation(s)
- Kamila Réblová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, CEITEC—Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Praha 6, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, CEITEC—Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Praha 6, Czech Republic
| | - Filip Lankaš
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, CEITEC—Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno and Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Praha 6, Czech Republic
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29
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Eichhorn CD, Feng J, Suddala KC, Walter NG, Brooks CL, Al-Hashimi HM. Unraveling the structural complexity in a single-stranded RNA tail: implications for efficient ligand binding in the prequeuosine riboswitch. Nucleic Acids Res 2011; 40:1345-55. [PMID: 22009676 PMCID: PMC3273816 DOI: 10.1093/nar/gkr833] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Single-stranded RNAs (ssRNAs) are ubiquitous RNA elements that serve diverse functional roles. Much of our understanding of ssRNA conformational behavior is limited to structures in which ssRNA directly engages in tertiary interactions or is recognized by proteins. Little is known about the structural and dynamic behavior of free ssRNAs at atomic resolution. Here, we report the collaborative application of nuclear magnetic resonance (NMR) and replica exchange molecular dynamics (REMD) simulations to characterize the 12 nt ssRNA tail derived from the prequeuosine riboswitch. NMR carbon spin relaxation data and residual dipolar coupling measurements reveal a flexible yet stacked core adopting an A-form-like conformation, with the level of order decreasing toward the terminal ends. An A-to-C mutation within the polyadenine tract alters the observed dynamics consistent with the introduction of a dynamic kink. Pre-ordering of the tail may increase the efficacy of ligand binding above that achieved by a random-coil ssRNA. The REMD simulations recapitulate important trends in the NMR data, but suggest more internal motions than inferred from the NMR analysis. Our study unmasks a previously unappreciated level of complexity in ssRNA, which we believe will also serve as an excellent model system for testing and developing computational force fields.
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Affiliation(s)
- Catherine D Eichhorn
- Chemical Biology Doctoral Program, University of Michigan, Ann Arbor, MI 48109, USA
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30
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Mustoe AM, Bailor MH, Teixeira RM, Brooks CL, Al-Hashimi HM. New insights into the fundamental role of topological constraints as a determinant of two-way junction conformation. Nucleic Acids Res 2011; 40:892-904. [PMID: 21937512 PMCID: PMC3258142 DOI: 10.1093/nar/gkr751] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Recent studies have shown that topological constraints encoded at the RNA secondary structure level involving basic steric and stereochemical forces can significantly restrict the orientations sampled by helices across two-way RNA junctions. Here, we formulate these topological constraints in greater quantitative detail and use this topological framework to rationalize long-standing but poorly understood observations regarding the basic behavior of RNA two-way junctions. Notably, we show that the asymmetric nature of the A-form helix and the finite length of a bulge provide a physical basis for the experimentally observed directionality and bulge-length amplitude dependence of bulge induced inter-helical bends. We also find that the topologically allowed space can be modulated by variations in sequence, particularly with the addition of non-canonical GU base pairs at the junction, and, surprisingly, by the length of the 5′ and 3′ helices. A survey of two-way RNA junctions in the protein data bank confirms that junction residues have a strong preference to adopt looped-in, non-canonically base-paired conformations, providing a route for extending our bulge-directed framework to internal loop motifs and implying a simplified link between secondary and tertiary structure. Finally, our results uncover a new simple mechanism for coupling junction-induced topological constraints with tertiary interactions.
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Affiliation(s)
- Anthony M Mustoe
- Departments of Chemistry & Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, MI 48109-1055, USA
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31
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Abstract
More than 50% of RNA secondary structure is estimated to be A-form helices, which are linked together by various junctions. Here we describe a protocol for computing three interhelical Euler angles describing the relative orientation of helices across RNA junctions. 5' and 3' helices, H1 and H2, respectively, are assigned based on the junction topology. A reference canonical helix is constructed using an appropriate molecular builder software consisting of two continuous idealized A-form helices (iH1 and iH2) with helix axis oriented along the molecular Z-direction running toward the positive direction from iH1 to iH2. The phosphate groups and the carbon and oxygen atoms of the sugars are used to superimpose helix H1 of a target interhelical junction onto the corresponding iH1 of the reference helix. A copy of iH2 is then superimposed onto the resulting H2 helix to generate iH2'. A rotation matrix R is computed, which rotates iH2' into iH2 and expresses the rotation parameters in terms of three Euler angles α(h), β(h) and γ(h). The angles are processed to resolve a twofold degeneracy and to select an overall rotation around the axis of the reference helix. The three interhelical Euler angles define clockwise rotations around the 5' (-γ(h)) and 3' (α(h)) helices and an interhelical bend angle (β(h)). The angles can be depicted graphically to provide a 'Ramachandran'-type view of RNA global structure that can be used to identify unusual conformations as well as to understand variations due to changes in sequence, junction topology and other parameters.
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32
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Topological constraints: using RNA secondary structure to model 3D conformation, folding pathways, and dynamic adaptation. Curr Opin Struct Biol 2011; 21:296-305. [PMID: 21497083 DOI: 10.1016/j.sbi.2011.03.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/10/2011] [Accepted: 03/22/2011] [Indexed: 12/14/2022]
Abstract
Accompanying recent advances in determining RNA secondary structure is the growing appreciation for the importance of relatively simple topological constraints, encoded at the secondary structure level, in defining the overall architecture, folding pathways, and dynamic adaptability of RNA. A new view is emerging in which tertiary interactions do not define RNA 3D structure, but rather, help select specific conformers from an already narrow, topologically pre-defined conformational distribution. Studies are providing fundamental insights into the nature of these topological constraints, how they are encoded by the RNA secondary structure, and how they interplay with other interactions, breathing new meaning to RNA secondary structure. New approaches have been developed that take advantage of topological constraints in determining RNA backbone conformation based on secondary structure, and a limited set of other, easily accessible constraints. Topological constraints are also providing a much-needed framework for rationalizing and describing RNA dynamics and structural adaptation. Finally, studies suggest that topological constraints may play important roles in steering RNA folding pathways. Here, we review recent advances in our understanding of topological constraints encoded by the RNA secondary structure.
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33
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Zhang Q, Kang M, Peterson RD, Feigon J. Comparison of solution and crystal structures of preQ1 riboswitch reveals calcium-induced changes in conformation and dynamics. J Am Chem Soc 2011; 133:5190-3. [PMID: 21410253 PMCID: PMC3085290 DOI: 10.1021/ja111769g] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
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Riboswitches regulate gene expression via specific recognition of cognate metabolites by their aptamer domains, which fold into stable conformations upon ligand binding. However, the recently reported solution and crystal structures of the Bacillus subtilis preQ1 riboswitch aptamer show small but significant differences, suggesting that there may be conformational heterogeneity in the ligand-bound state. We present a structural and dynamic characterization of this aptamer by solution NMR spectroscopy. The aptamer−preQ1 complex is intrinsically flexible in solution, with two regions that undergo motions on different time scales. Three residues move in concert on the micro-to-millisecond time scale and may serve as the lid of the preQ1-binding pocket. Several Ca2+ ions are present in the crystal structure, one of which binds with an affinity of 47 ± 2 μM in solution to a site that is formed only upon ligand binding. Addition of Ca2+ to the aptamer−preQ1 complex in solution results in conformational changes that account for the differences between the solution and crystal structures. Remarkably, the Ca2+ ions present in the crystal structure, which were proposed to be important for folding and ligand recognition, are not required for either in solution.
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Affiliation(s)
- Qi Zhang
- Department of Chemistry and Biochemistry , University of California, Los Angeles, California 90095-1569, USA
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34
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Dominguez C, Schubert M, Duss O, Ravindranathan S, Allain FHT. Structure determination and dynamics of protein-RNA complexes by NMR spectroscopy. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2011; 58:1-61. [PMID: 21241883 DOI: 10.1016/j.pnmrs.2010.10.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 04/24/2010] [Indexed: 05/30/2023]
Affiliation(s)
- Cyril Dominguez
- Institute for Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
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35
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Structurally conserved five nucleotide bulge determines the overall topology of the core domain of human telomerase RNA. Proc Natl Acad Sci U S A 2010; 107:18761-8. [PMID: 20966348 DOI: 10.1073/pnas.1013269107] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Telomerase is a unique ribonucleoprotein complex that catalyzes the addition of telomeric DNA repeats onto the 3' ends of linear chromosomes. All vertebrate telomerase RNAs contain a catalytically essential core domain that includes the template and a pseudoknot with extended helical subdomains. Within these helical regions is an asymmetric 5-nt internal bulge loop (J2a/b) flanked by helices (P2a and P2b) that is highly conserved in its location but not sequence. NMR structure determination reveals that J2a/b forms a defined S-shape and creates an ∼90 ° bend with a surprisingly low twist (∼10 °) between the flanking helices. A search of RNA structures revealed only one other example of a 5-nt bulge, from hepatitis C virus internal ribosome entry site, with a different sequence but the same structure. J2a/b is intrinsically flexible but the interhelical motions across the loop are remarkably restricted. Nucleotide substitutions in J2a/b that affect the bend angle, direction, and interhelical dynamics are correlated with telomerase activity. Based on the structures of P2ab (J2a/b and flanking helices), the conserved region of the pseudoknot (P2b/P3, previously determined) and the remaining helical segment (P2a.1-J2a.1 refined using residual dipolar couplings and the modeling program MC-Sym) we have calculated an NMR-based model of the full-length pseudoknot. The model and dynamics analysis show that J2a/b serves as a dominant structural and dynamical element in defining the overall topology of the core domain, and suggest that interhelical motions in P2ab facilitate nucleotide addition along the template and template translocation.
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36
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Dethoff EA, Hansen AL, Zhang Q, Al-Hashimi HM. Variable helix elongation as a tool to modulate RNA alignment and motional couplings. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 202:117-21. [PMID: 19854083 PMCID: PMC3319148 DOI: 10.1016/j.jmr.2009.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 09/23/2009] [Accepted: 09/26/2009] [Indexed: 05/13/2023]
Abstract
The application of residual dipolar couplings (RDCs) in studies of RNA structure and dynamics can be complicated by the presence of couplings between collective helix motions and overall alignment and by the inability to modulate overall alignment of the molecule by changing the ordering medium. Here, we show for a 27-nt TAR RNA construct that variable levels of helix elongation can be used to alter both overall alignment and couplings to collective helix motions in a semi-predictable manner. In the absence of elongation, a four base-pair helix II capped by a UUCG apical loop exhibits a higher degree of order compared to a six base-pair helix I (theta(I)/theta(II)=0.56+/-0.1). The principal S(zz) direction is nearly parallel to the axis of helix II but deviates by approximately 40 degrees relative to the axis of helix I. Elongating helix I by three base-pairs equalizes the alignment of the two helices and pushes the RNA into the motional coupling limit such that the two helices have comparable degrees of order (theta(I)/theta(II)=0.92+/-0.04) and orientations relative to S(zz) ( approximately 17 degrees ). Increasing the length of elongation further to 22 base-pairs pushes the RNA into the motional decoupling limit in which helix I dominates alignment (theta(II)/theta(I)=0.45+/-0.05), with S(zz) orientated nearly parallel to its helix axis. Many of these trends can be rationalized using PALES simulations that employ a previously proposed three-state dynamic ensemble of TAR. Our results provide new insights into motional couplings, offer guidelines for assessing their extent, and suggest that variable degrees of helix elongation can allow access to independent sets of RDCs for characterizing RNA structural dynamics.
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Affiliation(s)
- Elizabeth A. Dethoff
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alexandar L. Hansen
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Departments of Molecular Genetics, Biochemistry, and Chemistry, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Qi Zhang
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Hashim M. Al-Hashimi
- Department of Chemistry and Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- To whom correspondence should be addressed. H. M. A.: ; telephone (734) 615 3361; fax (734) 647 4865
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37
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Stelzer AC, Frank AT, Bailor MH, Andricioaei I, Al-Hashimi HM. Constructing atomic-resolution RNA structural ensembles using MD and motionally decoupled NMR RDCs. Methods 2009; 49:167-73. [PMID: 19699798 DOI: 10.1016/j.ymeth.2009.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 08/15/2009] [Accepted: 08/18/2009] [Indexed: 12/30/2022] Open
Abstract
A broad structural landscape often needs to be characterized in order to fully understand how regulatory RNAs perform their biological functions at the atomic level. We present a protocol for visualizing thermally accessible RNA conformations at atomic-resolution and with timescales extending up to milliseconds. The protocol combines molecular dynamics (MD) simulations with experimental residual dipolar couplings (RDCs) measured in partially aligned (13)C/(15)N isotopically enriched elongated RNA samples. The structural ensembles generated in this manner provide insights into RNA dynamics and its role in functionally important transitions.
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Affiliation(s)
- Andrew C Stelzer
- Department of Chemistry and Biophysics, The University of Michigan, Ann Arbor, MI 48109, USA
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38
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Farjon J, Boisbouvier J, Schanda P, Pardi A, Simorre JP, Brutscher B. Longitudinal-relaxation-enhanced NMR experiments for the study of nucleic acids in solution. J Am Chem Soc 2009; 131:8571-7. [PMID: 19485365 DOI: 10.1021/ja901633y] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Atomic-resolution information on the structure and dynamics of nucleic acids is essential for a better understanding of the mechanistic basis of many cellular processes. NMR spectroscopy is a powerful method for studying the structure and dynamics of nucleic acids; however, solution NMR studies are currently limited to relatively small nucleic acids at high concentrations. Thus, technological and methodological improvements that increase the experimental sensitivity and spectral resolution of NMR spectroscopy are required for studies of larger nucleic acids or protein-nucleic acid complexes. Here we introduce a series of imino-proton-detected NMR experiments that yield an over 2-fold increase in sensitivity compared to conventional pulse schemes. These methods can be applied to the detection of base pair interactions, RNA-ligand titration experiments, measurement of residual dipolar (15)N-(1)H couplings, and direct measurements of conformational transitions. These NMR experiments employ longitudinal spin relaxation enhancement techniques that have proven useful in protein NMR spectroscopy. The performance of these new experiments is demonstrated for a 10 kDa TAR-TAR*(GA) RNA kissing complex and a 26 kDa tRNA.
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Affiliation(s)
- Jonathan Farjon
- Institut de Biologie Structurale-Jean-Pierre Ebel, UMR5075 CNRS-CEA-UJF, 41, rue Jules Horowitz, 38027 Grenoble Cedex, France
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39
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Nelissen FHT, Girard FC, Tessari M, Heus HA, Wijmenga SS. Preparation of selective and segmentally labeled single-stranded DNA for NMR by self-primed PCR and asymmetrical endonuclease double digestion. Nucleic Acids Res 2009; 37:e114. [PMID: 19553193 PMCID: PMC2761255 DOI: 10.1093/nar/gkp540] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We demonstrate a new, efficient and easy-to-use method for enzymatic synthesis of (stereo-)specific and segmental (13)C/(15)N/(2)H isotope-labeled single-stranded DNA in amounts sufficient for NMR, based on the highly efficient self-primed PCR. To achieve this, new approaches are introduced and combined. (i) Asymmetric endonuclease double digestion of tandem-repeated PCR product. (ii) T4 DNA ligase mediated ligation of two ssDNA segments. (iii) In vitro dNTP synthesis, consisting of in vitro rNTP synthesis followed by enzymatic stereo-selective reduction of the C2' of the rNTP, and a one-pot add-up synthesis of dTTP from dUTP. The method is demonstrated on two ssDNAs: (i) a 36-nt three-way junction, selectively (13)C(9)/(15)N(3)/(2)H((1',2'',3',4',5',5''))-dC labeled and (ii) a 39-nt triple-repeat three-way junction, selectively (13)C(9)/(15)N(3)/(2)H((1',2'',3',4',5',5''))-dC and (13)C(9)/(15)N(2)/(2)H((1',2'',3',4',5',5''))-dT labeled in segment C20-C39. Their NMR spectra show the spectral simplification, while the stereo-selective (2)H-labeling in the deoxyribose of the dC-residues, straightforwardly provided assignment of their C1'-H2' and C2'-H2' resonances. The labeling protocols can be extended to larger ssDNA molecules and to more than two segments.
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Affiliation(s)
- Frank H T Nelissen
- Department of Biophysical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands
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40
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Fisher CK, Zhang Q, Stelzer A, Al-Hashimi HM. Ultrahigh resolution characterization of domain motions and correlations by multialignment and multireference residual dipolar coupling NMR. J Phys Chem B 2009; 112:16815-22. [PMID: 19367865 DOI: 10.1021/jp806188j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nuclear magnetic resonance (NMR) residual dipolar couplings (RDCs) provide a unique opportunity for spatially characterizing complex motions in biomolecules with time scale sensitivity extending up to milliseconds. Up to five motionally averaged Wigner rotation elements, (D(0k)2(alphaalpha)), can be determined experimentally using RDCs measured in five linearly independent alignment conditions and applied to define motions of axially symmetric bond vectors. Here, we show that up to 25 motionally averaged Wigner rotation elements, (D(mk)2(alphabetagamma)), can be determined experimentally from multialignment RDCs and used to characterize rigid-body motions of chiral domains. The 25 (D(mk)2(alphabetagamma)) elements form a basis set that allows one to measure motions of a domain relative to an isotropic distribution of reference frames anchored on a second domain (and vice versa), thus expanding the 3D spatial resolution with which motions can be characterized. The 25 (D(mk)2(alphabetagamma)) elements can also be used to fit an ensemble consisting of up to eight equally or six unequally populated states. For more than two domains, changing the identity of the domain governing alignment allows access to new information regarding the correlated nature of the domain fluctuations. Example simulations are provided that validate the theoretical derivation and illustrate the high spatial resolution with which rigid-body domain motions can be characterized using multialignment and multireference RDCs. Our results further motivate the development of experimental approaches for both modulating alignment and anchoring it on specifically targeted domains.
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Affiliation(s)
- Charles K Fisher
- Department of Chemistry & Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA
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41
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Frank AT, Stelzer AC, Al-Hashimi HM, Andricioaei I. Constructing RNA dynamical ensembles by combining MD and motionally decoupled NMR RDCs: new insights into RNA dynamics and adaptive ligand recognition. Nucleic Acids Res 2009; 37:3670-9. [PMID: 19369218 PMCID: PMC2699496 DOI: 10.1093/nar/gkp156] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We describe a strategy for constructing atomic resolution dynamical ensembles of RNA molecules, spanning up to millisecond timescales, that combines molecular dynamics (MD) simulations with NMR residual dipolar couplings (RDC) measured in elongated RNA. The ensembles are generated via a Monte Carlo procedure by selecting snap-shot from an MD trajectory that reproduce experimentally measured RDCs. Using this approach, we construct ensembles for two variants of the transactivation response element (TAR) containing three (HIV-1) and two (HIV-2) nucleotide bulges. The HIV-1 TAR ensemble reveals significant mobility in bulge residues C24 and U25 and to a lesser extent U23 and neighboring helical residue A22 that give rise to large amplitude spatially correlated twisting and bending helical motions. Omission of bulge residue C24 in HIV-2 TAR leads to a significant reduction in both the local mobility in and around the bulge and amplitude of inter-helical bending motions. In contrast, twisting motions of the helices remain comparable in amplitude to HIV-1 TAR and spatial correlations between them increase significantly. Comparison of the HIV-1 TAR dynamical ensemble and ligand bound TAR conformations reveals that several features of the binding pocket and global conformation are dynamically preformed, providing support for adaptive recognition via a ‘conformational selection’ type mechanism.
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Affiliation(s)
- Aaron T Frank
- Department of Chemistry, University of California Irvine, 1102 Natural Sciences 2, Irvine, CA 92697, USA
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42
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The preparation of site-specifically modified riboswitch domains as an example for enzymatic ligation of chemically synthesized RNA fragments. Nat Protoc 2008; 3:1457-66. [PMID: 18772873 DOI: 10.1038/nprot.2008.135] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This protocol describes an efficient method for the preparation of riboswitch domains comprising up to approximately 200 nt containing site-specific nucleoside modifications. The strategy is based on enzymatic ligation of chemically synthesized RNA fragments. The design of ligation sites strictly follows the criterion that all fragments comprise less than approximately 50 nt. This allows the researcher to rely on custom synthesis services and to utilize the large pool of commercially available, functionalized nucleoside phosphoramidites for solid-phase RNA synthesis. Importantly, this design renders utmost flexibility to position a chemical modification (e.g., a fluorescence label) within the RNA. Selection of the appropriate ligation type (using T4 RNA or T4 DNA ligase) is subordinate to the criteria above and is detailed in the protocol. The whole concept is demonstrated for 2-aminopurine containing thiamine pyrophosphate responsive riboswitch domains that are applied in fluorescence spectroscopic folding studies. Labeled samples in 5-35 nmol quantities are obtained within 3-4 d, not including the time for fragment synthesis.
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43
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Grishaev A, Ying J, Canny MD, Pardi A, Bax A. Solution structure of tRNAVal from refinement of homology model against residual dipolar coupling and SAXS data. JOURNAL OF BIOMOLECULAR NMR 2008; 42:99-109. [PMID: 18787959 PMCID: PMC2597493 DOI: 10.1007/s10858-008-9267-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 08/12/2008] [Accepted: 08/12/2008] [Indexed: 05/07/2023]
Abstract
A procedure is presented for refinement of a homology model of E. coli tRNA(Val), originally based on the X-ray structure of yeast tRNA(Phe), using experimental residual dipolar coupling (RDC) and small angle X-ray scattering (SAXS) data. A spherical sampling algorithm is described for refinement against SAXS data that does not require a globbic approximation, which is particularly important for nucleic acids where such approximations are less appropriate. Substantially higher speed of the algorithm also makes its application favorable for proteins. In addition to the SAXS data, the structure refinement employed a sparse set of NMR data consisting of 24 imino N-H(N) RDCs measured with Pf1 phage alignment, and 20 imino N-H(N) RDCs obtained from magnetic field dependent alignment of tRNA(Val). The refinement strategy aims to largely retain the local geometry of the 58% identical tRNA(Phe) by ensuring that the atomic coordinates for short, overlapping segments of the ribose-phosphate backbone and the conserved base pairs remain close to those of the starting model. Local coordinate restraints are enforced using the non-crystallographic symmetry (NCS) term in the XPLOR-NIH or CNS software package, while still permitting modest movements of adjacent segments. The RDCs mainly drive the relative orientation of the helical arms, whereas the SAXS restraints ensure an overall molecular shape compatible with experimental scattering data. The resulting structure exhibits good cross-validation statistics (jack-knifed Q (free) = 14% for the Pf1 RDCs, compared to 25% for the starting model) and exhibits a larger angle between the two helical arms than observed in the X-ray structure of tRNA(Phe), in agreement with previous NMR-based tRNA(Val) models.
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Affiliation(s)
- Alexander Grishaev
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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44
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Characterizing complex dynamics in the transactivation response element apical loop and motional correlations with the bulge by NMR, molecular dynamics, and mutagenesis. Biophys J 2008; 95:3906-15. [PMID: 18621815 DOI: 10.1529/biophysj.108.140285] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The HIV-1 transactivation response element (TAR) RNA binds a variety of proteins and is a target for developing anti-HIV therapies. TAR has two primary binding sites: a UCU bulge and a CUGGGA apical loop. We used NMR residual dipolar couplings, carbon spin relaxation (R(1) and R(2)), and relaxation dispersion (R(1rho)) in conjunction with molecular dynamics and mutagenesis to characterize the dynamics of the TAR apical loop and investigate previously proposed long-range interactions with the distant bulge. Replacement of the wild-type apical loop with a UUCG loop did not significantly affect the structural dynamics at the bulge, indicating that the apical loop and the bulge act largely as independent dynamical recognition centers. The apical loop undergoes complex dynamics at multiple timescales that are likely important for adaptive recognition: U31 and G33 undergo limited motions, G32 is highly flexible at picosecond-nanosecond timescales, and G34 and C30 form a dynamic Watson-Crick basepair in which G34 and A35 undergo a slow (approximately 30 mus) likely concerted looping in and out motion, with A35 also undergoing large amplitude motions at picosecond-nanosecond timescales. Our study highlights the power of combining NMR, molecular dynamics, and mutagenesis in characterizing RNA dynamics.
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Zhang Q, Stelzer AC, Fisher CK, Al-Hashimi HM. Visualizing spatially correlated dynamics that directs RNA conformational transitions. Nature 2008; 450:1263-7. [PMID: 18097416 DOI: 10.1038/nature06389] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Accepted: 10/18/2007] [Indexed: 01/27/2023]
Abstract
RNAs fold into three-dimensional (3D) structures that subsequently undergo large, functionally important, conformational transitions in response to a variety of cellular signals. RNA structures are believed to encode spatially tuned flexibility that can direct transitions along specific conformational pathways. However, this hypothesis has proved difficult to examine directly because atomic movements in complex biomolecules cannot be visualized in 3D by using current experimental methods. Here we report the successful implementation of a strategy using NMR that has allowed us to visualize, with complete 3D rotational sensitivity, the dynamics between two RNA helices that are linked by a functionally important trinucleotide bulge over timescales extending up to milliseconds. The key to our approach is to anchor NMR frames of reference onto each helix and thereby directly measure their dynamics, one relative to the other, using 'relativistic' sets of residual dipolar couplings (RDCs). Using this approach, we uncovered super-large amplitude helix motions that trace out a surprisingly structured and spatially correlated 3D dynamic trajectory. The two helices twist around their individual axes by approximately 53 degrees and 110 degrees in a highly correlated manner (R = 0.97) while simultaneously (R = 0.81-0.92) bending by about 94 degrees. Remarkably, the 3D dynamic trajectory is dotted at various positions by seven distinct ligand-bound conformations of the RNA. Thus even partly unstructured RNAs can undergo structured dynamics that directs ligand-induced transitions along specific predefined conformational pathways.
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Affiliation(s)
- Qi Zhang
- Department of Chemistry and Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA
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Musselman C, Al-Hashimi HM, Andricioaei I. iRED analysis of TAR RNA reveals motional coupling, long-range correlations, and a dynamical hinge. Biophys J 2007; 93:411-22. [PMID: 17449677 PMCID: PMC1896250 DOI: 10.1529/biophysj.107.104620] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The HIV-1 transactivation response RNA element (TAR), which is essential to the lifecycle of the virus, has been suggested, based on NMR and hydrodynamic measurements, to undergo substantial, collective, structural dynamics that are important for its function. To deal with the significant coupling between overall diffusional rotation and internal motion expected to exist in TAR, here we utilize an isotropic reorientational eigenmode dynamics analysis of simulated molecular trajectories to obtain a detailed description of TAR dynamics and an accurately quantified pattern of dynamical correlations. The analysis demonstrates the inseparability of internal and overall motional modes, confirms the existence and reveals the nature of collective domain dynamics, and additionally reveals that the hinge for these motions is centered on residues U23, C24, and C41. Results also indicate the existence of long-range communication between the loop and the core of the RNA, and between the loop and the bulge. Additionally, the isotropic reorientational eigenmode dynamics analysis explains, from a dynamical perspective, several existing biochemical mutational studies and suggests new mutations for future structural dynamics studies.
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Affiliation(s)
- Catherine Musselman
- Department of Chemistry and The Center for Computational Medicine and Biology, University of Michigan, Ann Arbor, Michigan, USA
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