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Schärfen L, Neugebauer KM. Transcription Regulation Through Nascent RNA Folding. J Mol Biol 2021; 433:166975. [PMID: 33811916 DOI: 10.1016/j.jmb.2021.166975] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/14/2022]
Abstract
Folding of RNA into secondary structures through intramolecular base pairing determines an RNA's three-dimensional architecture and associated function. Simple RNA structures like stem loops can provide specialized functions independent of coding capacity, such as protein binding, regulation of RNA processing and stability, stimulation or inhibition of translation. RNA catalysis is dependent on tertiary structures found in the ribosome, tRNAs and group I and II introns. While the extent to which non-coding RNAs contribute to cellular maintenance is generally appreciated, the fact that both non-coding and coding RNA can assume relevant structural states has only recently gained attention. In particular, the co-transcriptional folding of nascent RNA of all classes has the potential to regulate co-transcriptional processing, RNP (ribonucleoprotein particle) formation, and transcription itself. Riboswitches are established examples of co-transcriptionally folded coding RNAs that directly regulate transcription, mainly in prokaryotes. Here we discuss recent studies in both prokaryotes and eukaryotes showing that structure formation may carry a more widespread regulatory logic during RNA synthesis. Local structures forming close to the catalytic center of RNA polymerases have the potential to regulate transcription by reducing backtracking. In addition, stem loops or more complex structures may alter co-transcriptional RNA processing or its efficiency. Several examples of functional structures have been identified to date, and this review provides an overview of physiologically distinct processes where co-transcriptionally folded RNA plays a role. Experimental approaches such as single-molecule FRET and in vivo structural probing to further advance our insight into the significance of co-transcriptional structure formation are discussed.
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Affiliation(s)
- Leonard Schärfen
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Karla M Neugebauer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
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2
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Mitra S, Demeler B. Probing RNA-Protein Interactions and RNA Compaction by Sedimentation Velocity Analytical Ultracentrifugation. Methods Mol Biol 2020; 2113:281-317. [PMID: 32006321 PMCID: PMC10958623 DOI: 10.1007/978-1-0716-0278-2_19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Recent advances in multi-wavelength analytical ultracentrifugation (MWL-AUC) combine the power of an exquisitely sensitive hydrodynamic-based separation technique with the added dimension of spectral separation. This added dimension has opened up new doors to much improved characterization of multiple, interacting species in solution. When applied to structural investigations of RNA, MWL-AUC can precisely report on the hydrodynamic radius and the overall shape of an RNA molecule by enabling precise measurements of its sedimentation and diffusion coefficients and identify the stoichiometry of interacting components based on spectral decomposition. Information provided in this chapter will allow an investigator to design experiments for probing ion and/or protein-induced global conformational changes of an RNA molecule and exploit spectral differences between proteins and RNA to characterize their interactions in a physiological solution environment.
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Affiliation(s)
- Somdeb Mitra
- Department of Chemistry, New York University, New York, NY, USA.
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
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3
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Petersen NP, Ort T, Torda AE. Improving the Numerical Stability of the NAST Force Field for RNA Simulations. J Chem Theory Comput 2019; 15:3402-3409. [DOI: 10.1021/acs.jctc.9b00089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nils P. Petersen
- Centre for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany
| | - Thomas Ort
- Laboratory Automation and Biomanufacturing Engineering, Fraunhofer Institute for Manufacturing Engineering and Automation IPA, Nobelstrasse 12, 70569 Stuttgart, Germany
| | - Andrew E. Torda
- Centre for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany
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4
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Affiliation(s)
- Amanda Solem
- Department of Biology, Hastings College, Hastings, Nebraska, USA
| | - Alain Laederach
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, USA
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Mustoe AM, Al-Hashimi HM, Brooks CL. Secondary structure encodes a cooperative tertiary folding funnel in the Azoarcus ribozyme. Nucleic Acids Res 2015; 44:402-12. [PMID: 26481360 PMCID: PMC4705646 DOI: 10.1093/nar/gkv1055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 10/03/2015] [Indexed: 12/20/2022] Open
Abstract
A requirement for specific RNA folding is that the free-energy landscape discriminate against non-native folds. While tertiary interactions are critical for stabilizing the native fold, they are relatively non-specific, suggesting additional mechanisms contribute to tertiary folding specificity. In this study, we use coarse-grained molecular dynamics simulations to explore how secondary structure shapes the tertiary free-energy landscape of the Azoarcus ribozyme. We show that steric and connectivity constraints posed by secondary structure strongly limit the accessible conformational space of the ribozyme, and that these so-called topological constraints in turn pose strong free-energy penalties on forming different tertiary contacts. Notably, native A-minor and base-triple interactions form with low conformational free energy, while non-native tetraloop/tetraloop–receptor interactions are penalized by high conformational free energies. Topological constraints also give rise to strong cooperativity between distal tertiary interactions, quantitatively matching prior experimental measurements. The specificity of the folding landscape is further enhanced as tertiary contacts place additional constraints on the conformational space, progressively funneling the molecule to the native state. These results indicate that secondary structure assists the ribozyme in navigating the otherwise rugged tertiary folding landscape, and further emphasize topological constraints as a key force in RNA folding.
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Affiliation(s)
- Anthony M Mustoe
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Hashim M Al-Hashimi
- Department of Biochemistry and Chemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Charles L Brooks
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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Kerpedjiev P, Höner Zu Siederdissen C, Hofacker IL. Predicting RNA 3D structure using a coarse-grain helix-centered model. RNA (NEW YORK, N.Y.) 2015; 21:1110-1121. [PMID: 25904133 PMCID: PMC4436664 DOI: 10.1261/rna.047522.114] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
A 3D model of RNA structure can provide information about its function and regulation that is not possible with just the sequence or secondary structure. Current models suffer from low accuracy and long running times and either neglect or presume knowledge of the long-range interactions which stabilize the tertiary structure. Our coarse-grained, helix-based, tertiary structure model operates with only a few degrees of freedom compared with all-atom models while preserving the ability to sample tertiary structures given a secondary structure. It strikes a balance between the precision of an all-atom tertiary structure model and the simplicity and effectiveness of a secondary structure representation. It provides a simplified tool for exploring global arrangements of helices and loops within RNA structures. We provide an example of a novel energy function relying only on the positions of stems and loops. We show that coupling our model to this energy function produces predictions as good as or better than the current state of the art tools. We propose that given the wide range of conformational space that needs to be explored, a coarse-grain approach can explore more conformations in less iterations than an all-atom model coupled to a fine-grain energy function. Finally, we emphasize the overarching theme of providing an ensemble of predicted structures, something which our tool excels at, rather than providing a handful of the lowest energy structures.
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Affiliation(s)
| | - Christian Höner Zu Siederdissen
- Institute for Theoretical Chemistry, A-1090 Vienna, Austria Bioinformatics Group, Department of Computer Science, Universität Leipzig, D-04107 Leipzig, Germany Interdisciplinary Center for Bioinformatics, Universität Leipzig, D-04107 Leipzig, Germany
| | - Ivo L Hofacker
- Institute for Theoretical Chemistry, A-1090 Vienna, Austria Research Group Bioinformatics and Computational Biology, University of Vienna, A-1090 Vienna, Austria Center for non-coding RNA in Technology and Health, Department of Veterinary Clinical and Animal Science, University of Copenhagen, DK-1870 Frederiksberg, Denmark
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Corley M, Solem A, Qu K, Chang HY, Laederach A. Detecting riboSNitches with RNA folding algorithms: a genome-wide benchmark. Nucleic Acids Res 2015; 43:1859-68. [PMID: 25618847 PMCID: PMC4330374 DOI: 10.1093/nar/gkv010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Ribonucleic acid (RNA) secondary structure prediction continues to be a significant challenge, in particular when attempting to model sequences with less rigidly defined structures, such as messenger and non-coding RNAs. Crucial to interpreting RNA structures as they pertain to individual phenotypes is the ability to detect RNAs with large structural disparities caused by a single nucleotide variant (SNV) or riboSNitches. A recently published human genome-wide parallel analysis of RNA structure (PARS) study identified a large number of riboSNitches as well as non-riboSNitches, providing an unprecedented set of RNA sequences against which to benchmark structure prediction algorithms. Here we evaluate 11 different RNA folding algorithms’ riboSNitch prediction performance on these data. We find that recent algorithms designed specifically to predict the effects of SNVs on RNA structure, in particular remuRNA, RNAsnp and SNPfold, perform best on the most rigorously validated subsets of the benchmark data. In addition, our benchmark indicates that general structure prediction algorithms (e.g. RNAfold and RNAstructure) have overall better performance if base pairing probabilities are considered rather than minimum free energy calculations. Although overall aggregate algorithmic performance on the full set of riboSNitches is relatively low, significant improvement is possible if the highest confidence predictions are evaluated independently.
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Affiliation(s)
- Meredith Corley
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 37599, USA Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Amanda Solem
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 37599, USA
| | - Kun Qu
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Howard Y Chang
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Alain Laederach
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 37599, USA Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Mitra S. Detecting RNA tertiary folding by sedimentation velocity analytical ultracentrifugation. Methods Mol Biol 2014; 1086:265-88. [PMID: 24136610 DOI: 10.1007/978-1-62703-667-2_16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Analytical Ultracentrifugation (AUC) is a highly sensitive technique for detecting global conformational features of biological molecules and molecular interactions in solution. When operated in a sedimentation velocity (SV) recording mode, it reports precisely on the hydrodynamic properties of a molecule, including its sedimentation and diffusion coefficients, which can be used to calculate its hydrated radius, as well as, to estimate its global shape. This chapter describes the application of SV-AUC to the detection of global conformational changes accompanying equilibrium counterion induced tertiary folding of structured RNA molecules. A brief theoretical background is provided at the beginning, aimed at familiarizing the readers with the operational principle of the technique; then, a detailed set of instructions is provided on how to design, conduct, and analyze the data from an equilibrium RNA folding experiment, using SV-AUC.
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Affiliation(s)
- Somdeb Mitra
- Department of Chemistry, Columbia University, New York, NY, USA
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Evolutionary evidence for alternative structure in RNA sequence co-variation. PLoS Comput Biol 2013; 9:e1003152. [PMID: 23935473 PMCID: PMC3723493 DOI: 10.1371/journal.pcbi.1003152] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/05/2013] [Indexed: 02/06/2023] Open
Abstract
Sequence conservation and co-variation of base pairs are hallmarks of structured RNAs. For certain RNAs (e.g. riboswitches), a single sequence must adopt at least two alternative secondary structures to effectively regulate the message. If alternative secondary structures are important to the function of an RNA, we expect to observe evolutionary co-variation supporting multiple conformations. We set out to characterize the evolutionary co-variation supporting alternative conformations in riboswitches to determine the extent to which alternative secondary structures are conserved. We found strong co-variation support for the terminator, P1, and anti-terminator stems in the purine riboswitch by extending alignments to include terminator sequences. When we performed Boltzmann suboptimal sampling on purine riboswitch sequences with terminators we found that these sequences appear to have evolved to favor specific alternative conformations. We extended our analysis of co-variation to classic alignments of group I/II introns, tRNA, and other classes of riboswitches. In a majority of these RNAs, we found evolutionary evidence for alternative conformations that are compatible with the Boltzmann suboptimal ensemble. Our analyses suggest that alternative conformations are selected for and thus likely play functional roles in even the most structured of RNAs. RNA (Ribonucleic Acid) is a messenger of genetic information, master regulator, and catalyst in the cell. To carry out its function, RNA can fold into complex three-dimensional structures. Certain classes of RNAs, called riboswitches, adopt at least two alternative structures to act as a switch. We set out to detect the evolutionary signal for alternative structures in riboswitches as we hypothesize that these RNA sequences must have evolved to allow both conformations. We find that indeed such signals exist when we compare the sequences of riboswitches from multiple species. When we extend this analysis to other RNA regulators in the cell that are not thought of as switches, we detect equivalent evolutionary support for alternative structures. Viewed through the lens of evolutionary structure conservation RNA sequences appear to have adapted to adopt multiple conformations.
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