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Thiel BC, Bussi G, Poblete S, Hofacker IL. Sampling globally and locally correct RNA 3D structures using Ernwin, SPQR and experimental SAXS data. Nucleic Acids Res 2024:gkae602. [PMID: 39021350 DOI: 10.1093/nar/gkae602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 07/05/2024] [Indexed: 07/20/2024] Open
Abstract
The determination of the three-dimensional structure of large RNA macromolecules in solution is a challenging task that often requires the use of several experimental and computational techniques. Small-angle X-ray scattering can provide insight into some geometrical properties of the probed molecule, but this data must be properly interpreted in order to generate a three-dimensional model. Here, we propose a multiscale pipeline which introduces SAXS data into modelling the global shape of RNA in solution, which can be hierarchically refined until reaching atomistic precision in explicit solvent. The low-resolution helix model (Ernwin) deals with the exploration of the huge conformational space making use of the SAXS data, while a nucleotide-level model (SPQR) removes clashes and disentangles the proposed structures, leading the structure to an all-atom representation in explicit water. We apply the procedure on four different known pdb structures up to 159 nucleotides with promising results. Additionally, we predict an all-atom structure for the Plasmodium falceparum signal recognition particle ALU RNA based on SAXS data deposited in the SASBDB, which has an alternate conformation and better fit to the SAXS data than the previously published structure based on the same data but other modelling methods.
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Affiliation(s)
- Bernhard C Thiel
- Department of Theoretical Chemistry, University of Vienna, Währinger Strasse 17, Vienna 1090, Austria
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati, SISSA, via Bonomea 265, Trieste 34136, Italy
| | - Simón Poblete
- Centro BASAL Ciencia & Vida, Avenida del Valle Norte 725, Santiago 8580702, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista 7, Santiago 8420524, Chile
| | - Ivo L Hofacker
- Department of Theoretical Chemistry, University of Vienna, Währinger Strasse 17, Vienna 1090, Austria
- Research group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna 1090, Austria
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Thiel BC, Poblete S, Hofacker IL. The Multiscale Ernwin/SPQR RNA Structure Prediction Pipeline. Methods Mol Biol 2024; 2726:377-399. [PMID: 38780739 DOI: 10.1007/978-1-0716-3519-3_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Aside from the well-known role in protein synthesis, RNA can perform catalytic, regulatory, and other essential biological functions which are determined by its three-dimensional structure. In this regard, a great effort has been made during the past decade to develop computational tools for the prediction of the structure of RNAs from the knowledge of their sequence, incorporating experimental data to refine or guide the modeling process. Nevertheless, this task can become exceptionally challenging when dealing with long noncoding RNAs, constituted by more than 200 nucleotides, due to their large size and the specific interactions involved. In this chapter, we describe a multiscale approach to predict such structures, incorporating SAXS experimental data into a hierarchical procedure which couples two coarse-grained representations: Ernwin, a helix-based approach, which deals with the global arrangement of secondary structure elements, and SPQR, a nucleotide-centered coarse-grained model, which corrects and refines the structures predicted at the coarser level.We describe the methodology through its application on the Braveheart long noncoding RNA, starting from the SAXS and secondary structure data to propose a refined, all-atom structure.
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Affiliation(s)
- Bernhard C Thiel
- Department of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Simón Poblete
- Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile, Valdivia, Chile
- Computational Biology Lab, Fundación Ciencia & Vida, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad SanSebastián, Santiago, Chile
| | - Ivo L Hofacker
- Department of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria.
- Research Group Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria.
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Chojnowski G, Zaborowski R, Magnus M, Mukherjee S, Bujnicki JM. RNA 3D structure modeling by fragment assembly with small-angle X-ray scattering restraints. Bioinformatics 2023; 39:btad527. [PMID: 37647627 PMCID: PMC10474949 DOI: 10.1093/bioinformatics/btad527] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/14/2023] [Accepted: 08/28/2023] [Indexed: 09/01/2023] Open
Abstract
SUMMARY Structure determination is a key step in the functional characterization of many non-coding RNA molecules. High-resolution RNA 3D structure determination efforts, however, are not keeping up with the pace of discovery of new non-coding RNA sequences. This increases the importance of computational approaches and low-resolution experimental data, such as from the small-angle X-ray scattering experiments. We present RNA Masonry, a computer program and a web service for a fully automated modeling of RNA 3D structures. It assemblies RNA fragments into geometrically plausible models that meet user-provided secondary structure constraints, restraints on tertiary contacts, and small-angle X-ray scattering data. We illustrate the method description with detailed benchmarks and its application to structural studies of viral RNAs with SAXS restraints. AVAILABILITY AND IMPLEMENTATION The program web server is available at http://iimcb.genesilico.pl/rnamasonry. The source code is available at https://gitlab.com/gchojnowski/rnamasonry.
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Affiliation(s)
- Grzegorz Chojnowski
- International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg 22607, Germany
| | - Rafał Zaborowski
- International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland
| | - Marcin Magnus
- ReMedy International Research Agenda Unit, IMol Polish Academy of Sciences, Warsaw, Poland
| | - Sunandan Mukherjee
- International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland
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Sabei A, Caldas Baia TG, Saffar R, Martin J, Frezza E. Internal Normal Mode Analysis Applied to RNA Flexibility and Conformational Changes. J Chem Inf Model 2023; 63:2554-2572. [PMID: 36972178 DOI: 10.1021/acs.jcim.2c01509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
We investigated the capability of internal normal modes to reproduce RNA flexibility and predict observed RNA conformational changes and, notably, those induced by the formation of RNA-protein and RNA-ligand complexes. Here, we extended our iNMA approach developed for proteins to study RNA molecules using a simplified representation of the RNA structure and its potential energy. Three data sets were also created to investigate different aspects. Despite all the approximations, our study shows that iNMA is a suitable method to take into account RNA flexibility and describe its conformational changes opening the route to its applicability in any integrative approach where these properties are crucial.
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Monsen RC, DeLeeuw LW, Dean W, Gray R, Chakravarthy S, Hopkins J, Chaires J, Trent J. Long promoter sequences form higher-order G-quadruplexes: an integrative structural biology study of c-Myc, k-Ras and c-Kit promoter sequences. Nucleic Acids Res 2022; 50:4127-4147. [PMID: 35325198 PMCID: PMC9023277 DOI: 10.1093/nar/gkac182] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Accepted: 03/21/2022] [Indexed: 12/15/2022] Open
Abstract
We report on higher-order G-quadruplex structures adopted by long promoter sequences obtained by an iterative integrated structural biology approach. Our approach uses quantitative biophysical tools (analytical ultracentrifugation, small-angle X-ray scattering, and circular dichroism spectroscopy) combined with modeling and molecular dynamics simulations, to derive self-consistent structural models. The formal resolution of our approach is 18 angstroms, but in some cases structural features of only a few nucleotides can be discerned. We report here five structures of long (34-70 nt) wild-type sequences selected from three cancer-related promoters: c-Myc, c-Kit and k-Ras. Each sequence studied has a unique structure. Three sequences form structures with two contiguous, stacked, G-quadruplex units. One longer sequence from c-Myc forms a structure with three contiguous stacked quadruplexes. A longer c-Kit sequence forms a quadruplex-hairpin structure. Each structure exhibits interfacial regions between stacked quadruplexes or novel loop geometries that are possible druggable targets. We also report methodological advances in our integrated structural biology approach, which now includes quantitative CD for counting stacked G-tetrads, DNaseI cleavage for hairpin detection and SAXS model refinement. Our results suggest that higher-order quadruplex assemblies may be a common feature within the genome, rather than simple single quadruplex structures.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Lynn W DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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Computer-aided comprehensive explorations of RNA structural polymorphism through complementary simulation methods. QRB DISCOVERY 2022. [PMID: 37529277 PMCID: PMC10392686 DOI: 10.1017/qrd.2022.19] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
While RNA folding was originally seen as a simple problem to solve, it has been shown that the promiscuous interactions of the nucleobases result in structural polymorphism, with several competing structures generally observed for non-coding RNA. This inherent complexity limits our understanding of these molecules from experiments alone, and computational methods are commonly used to study RNA. Here, we discuss three advanced sampling schemes, namely Hamiltonian-replica exchange molecular dynamics (MD), ratchet-and-pawl MD and discrete path sampling, as well as the HiRE-RNA coarse-graining scheme, and highlight how these approaches are complementary with reference to recent case studies. While all computational methods have their shortcomings, the plurality of simulation methods leads to a better understanding of experimental findings and can inform and guide experimental work on RNA polymorphism.
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