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Backofen R, Gorodkin J, Hofacker IL, Stadler PF. Comparative RNA Genomics. Methods Mol Biol 2024; 2802:347-393. [PMID: 38819565 DOI: 10.1007/978-1-0716-3838-5_12] [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: 06/01/2024]
Abstract
Over the last quarter of a century it has become clear that RNA is much more than just a boring intermediate in protein expression. Ancient RNAs still appear in the core information metabolism and comprise a surprisingly large component in bacterial gene regulation. A common theme with these types of mostly small RNAs is their reliance of conserved secondary structures. Large-scale sequencing projects, on the other hand, have profoundly changed our understanding of eukaryotic genomes. Pervasively transcribed, they give rise to a plethora of large and evolutionarily extremely flexible non-coding RNAs that exert a vastly diverse array of molecule functions. In this chapter we provide a-necessarily incomplete-overview of the current state of comparative analysis of non-coding RNAs, emphasizing computational approaches as a means to gain a global picture of the modern RNA world.
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Affiliation(s)
- Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Freiburg, Germany
- Center for Non-coding RNA in Technology and Health, University of Copenhagen, Frederiksberg, Denmark
| | - Jan Gorodkin
- Center for Non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Ivo L Hofacker
- Institute for Theoretical Chemistry, University of Vienna, Wien, Austria
- Bioinformatics and Computational Biology research group, University of Vienna, Vienna, Austria
- Center for Non-coding RNA in Technology and Health, University of Copenhagen, Frederiksberg, Denmark
| | - Peter F Stadler
- Bioinformatics Group, Department of Computer Science, University of Leipzig, Leipzig, Germany.
- Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany.
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany.
- Universidad National de Colombia, Bogotá, Colombia.
- Institute for Theoretical Chemistry, University of Vienna, Wien, Austria.
- Center for Non-coding RNA in Technology and Health, University of Copenhagen, Frederiksberg, Denmark.
- Santa Fe Institute, Santa Fe, NM, USA.
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Walter Costa MB, Höner zu Siederdissen C, Dunjić M, Stadler PF, Nowick K. SSS-test: a novel test for detecting positive selection on RNA secondary structure. BMC Bioinformatics 2019; 20:151. [PMID: 30898084 PMCID: PMC6429701 DOI: 10.1186/s12859-019-2711-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 03/03/2019] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Long non-coding RNAs (lncRNAs) play an important role in regulating gene expression and are thus important for determining phenotypes. Most attempts to measure selection in lncRNAs have focused on the primary sequence. The majority of small RNAs and at least some parts of lncRNAs must fold into specific structures to perform their biological function. Comprehensive assessments of selection acting on RNAs therefore must also encompass structure. Selection pressures acting on the structure of non-coding genes can be detected within multiple sequence alignments. Approaches of this type, however, have so far focused on negative selection. Thus, a computational method for identifying ncRNAs under positive selection is needed. RESULTS We introduce the SSS-test (test for Selection on Secondary Structure) to identify positive selection and thus adaptive evolution. Benchmarks with biological as well as synthetic controls yield coherent signals for both negative and positive selection, demonstrating the functionality of the test. A survey of a lncRNA collection comprising 15,443 families resulted in 110 candidates that appear to be under positive selection in human. In 26 lncRNAs that have been associated with psychiatric disorders we identified local structures that have signs of positive selection in the human lineage. CONCLUSIONS It is feasible to assay positive selection acting on RNA secondary structures on a genome-wide scale. The detection of human-specific positive selection in lncRNAs associated with cognitive disorder provides a set of candidate genes for further experimental testing and may provide insights into the evolution of cognitive abilities in humans. AVAILABILITY The SSS-test and related software is available at: https://github.com/waltercostamb/SSS-test . The databases used in this work are available at: http://www.bioinf.uni-leipzig.de/Software/SSS-test/ .
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Affiliation(s)
- Maria Beatriz Walter Costa
- Embrapa Agroenergia, Parque Estação Biológica (PqEB), Asa Norte, Brasília, DF, 70770-901 Brazil
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, Leipzig, 04107 Germany
| | - Christian Höner zu Siederdissen
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, Leipzig, 04107 Germany
| | - Marko Dunjić
- Human Biology Group, Institute for Biology, Department of Biology, Chemistry, Pharmacy, Freie Universitaet Berlin, Königin-Luise-Straße 1-3, Berlin, 14195 Germany
- Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Studentski trg 16, PO box 43, Belgrade, 11000 Serbia
| | - Peter F. Stadler
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, Leipzig, 04107 Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig & Competence Center for Scalable Data Services and Solutions Dresden-Leipzig & Leipzig Research Center for Civilization Diseases, University Leipzig, Leipzig, 04107 Germany
- Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, Leipzig, 04103 Germany
- Department of Theoretical Chemistry, University of Vienna, Währinger Straße 17, Vienna, A-1090 Austria
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Faculdad de Ciencias, Universidad Nacional de Colombia, Sede Bogotá, Ciudad Universitaria, Bogotá, D.C., COL-111321 Colombia
- Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM87501 USA
| | - Katja Nowick
- Human Biology Group, Institute for Biology, Department of Biology, Chemistry, Pharmacy, Freie Universitaet Berlin, Königin-Luise-Straße 1-3, Berlin, 14195 Germany
- TFome Research Group, Bioinformatics Group, Interdisciplinary Center of Bioinformatics, Department of Computer Science, University of Leipzig, Härtelstraße 16-18, Leipzig, 04107 Germany
- Paul-Flechsig-Institute for Brain Research, University of Leipzig, Liebigstraße 19. Haus C, Leipzig, 04103 Germany
- Bioinformatics, Faculty of Agricultural Sciences, Institute of Animal Science, University of Hohenheim, Garbenstraße 13, Stuttgart, 70593 Germany
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Kirsch R, Seemann SE, Ruzzo WL, Cohen SM, Stadler PF, Gorodkin J. Identification and characterization of novel conserved RNA structures in Drosophila. BMC Genomics 2018; 19:899. [PMID: 30537930 PMCID: PMC6288889 DOI: 10.1186/s12864-018-5234-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 11/08/2018] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Comparative genomics approaches have facilitated the discovery of many novel non-coding and structured RNAs (ncRNAs). The increasing availability of related genomes now makes it possible to systematically search for compensatory base changes - and thus for conserved secondary structures - even in genomic regions that are poorly alignable in the primary sequence. The wealth of available transcriptome data can add valuable insight into expression and possible function for new ncRNA candidates. Earlier work identifying ncRNAs in Drosophila melanogaster made use of sequence-based alignments and employed a sliding window approach, inevitably biasing identification toward RNAs encoded in the more conserved parts of the genome. RESULTS To search for conserved RNA structures (CRSs) that may not be highly conserved in sequence and to assess the expression of CRSs, we conducted a genome-wide structural alignment screen of 27 insect genomes including D. melanogaster and integrated this with an extensive set of tiling array data. The structural alignment screen revealed ∼30,000 novel candidate CRSs at an estimated false discovery rate of less than 10%. With more than one quarter of all individual CRS motifs showing sequence identities below 60%, the predicted CRSs largely complement the findings of sliding window approaches applied previously. While a sixth of the CRSs were ubiquitously expressed, we found that most were expressed in specific developmental stages or cell lines. Notably, most statistically significant enrichment of CRSs were observed in pupae, mainly in exons of untranslated regions, promotors, enhancers, and long ncRNAs. Interestingly, cell lines were found to express a different set of CRSs than were found in vivo. Only a small fraction of intergenic CRSs were co-expressed with the adjacent protein coding genes, which suggests that most intergenic CRSs are independent genetic units. CONCLUSIONS This study provides a more comprehensive view of the ncRNA transcriptome in fly as well as evidence for differential expression of CRSs during development and in cell lines.
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Affiliation(s)
- Rebecca Kirsch
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Department of Veterinary and Animal Science, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, Leipzig, D-04107 Germany
| | - Stefan E. Seemann
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Department of Veterinary and Animal Science, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
| | - Walter L. Ruzzo
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- School of Computer Science and Engineering, University of Washington, Box 352350, Seattle, 98195-2350 WA USA
- Department of Genome Sciences, University of Washington, Box 355065, Seattle, 98195-5065 WA USA
- Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N., Seattle, 98109-1024 WA USA
| | - Stephen M. Cohen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, Copenhagen N, DK-2200 Denmark
| | - Peter F. Stadler
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics, Universität Leipzig, Härtelstraße 16–18, Leipzig, D-04107 Germany
- Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, Leipzig, D-04103 Germany
- Faculdad de Ciencias, Universidad Nacional de Colombia, Sede Bogotá, Ciudad Universitaria, Bogotá, COL-111321 D.C. Colombia
- Department of Theoretical Chemistry, University of Vienna, Währinger Straße 17, Vienna, A-1090 Austria
- Santa Fe Institute, 1399 Hyde Park Rd., Santa Fe, NM87501 USA
| | - Jan Gorodkin
- Center for non-coding RNA in Technology and Health, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
- Department of Veterinary and Animal Science, University of Copenhagen, Grønnegårdsvej 3, Frederiksberg C, DK-1870 Denmark
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Abstract
Over the last two decades it has become clear that RNA is much more than just a boring intermediate in protein expression. Ancient RNAs still appear in the core information metabolism and comprise a surprisingly large component in bacterial gene regulation. A common theme with these types of mostly small RNAs is their reliance of conserved secondary structures. Large scale sequencing projects, on the other hand, have profoundly changed our understanding of eukaryotic genomes. Pervasively transcribed, they give rise to a plethora of large and evolutionarily extremely flexible noncoding RNAs that exert a vastly diverse array of molecule functions. In this chapter we provide a-necessarily incomplete-overview of the current state of comparative analysis of noncoding RNAs, emphasizing computational approaches as a means to gain a global picture of the modern RNA world.
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Affiliation(s)
- Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, Georges-Köhler-Allee 106, D-79110 Freiburg, Germany.,Center for non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 3, DK-1870 Frederiksberg C, Denmark
| | - Jan Gorodkin
- Center for non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 3, DK-1870 Frederiksberg C, Denmark
| | - Ivo L Hofacker
- Center for non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 3, DK-1870 Frederiksberg C, Denmark.,Institute for Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Wien, Austria.,Bioinformatics and Computational Biology Research Group, University of Vienna, Währingerstraße 17, A-1090 Vienna, Austria
| | - Peter F Stadler
- Center for non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 3, DK-1870 Frederiksberg C, Denmark. .,Institute for Theoretical Chemistry, University of Vienna, Währingerstraße 17, A-1090 Wien, Austria. .,Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics, University of Leipzig, Härtelstraße 16-18, D-04107 Leipzig, Germany. .,Max Planck Institute for Mathematics in the Sciences, Inselstraße 22, D-04103 Leipzig, Germany. .,Fraunhofer Institute for Cell Therapy and Immunology, Perlickstraße 1, D-04103 Leipzig, Germany. .,Santa Fe Institute, 1399 Hyde Park Rd, Santa Fe, NM 87501, USA.
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Kusumi J, Ichinose M, Takefu M, Piskol R, Stephan W, Iizuka M. A model of compensatory molecular evolution involving multiple sites in RNA molecules. J Theor Biol 2015; 388:96-107. [PMID: 26506471 DOI: 10.1016/j.jtbi.2015.10.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/17/2015] [Accepted: 10/14/2015] [Indexed: 11/16/2022]
Abstract
Consider two sites under compensatory fitness interaction, such as a Watson-Crick base pair in an RNA helix or two interacting residues in a protein. A mutation at any one of these two sites may reduce the fitness of an individual. However, fitness may be restored by the occurrence of a second mutation at the other site. Kimura modeled this process using a two-locus haploid fitness scheme with two alleles at each locus. He predicted that compensatory evolution following this model is very rare unless selection against the deleterious single mutations is weak and linkage between the interacting sites is tight. Here we investigate the question whether the rate of compensatory evolution increases if we take the context of the two directly interacting sites into account. By "context", we mean the effect of neighboring sites in an RNA helix. Interaction between the focal pair of sites under consideration and the context may lead to so-called indirect compensation. Thus, extending Kimura's classical model of compensatory evolution, we study the effects of both direct and indirect compensation on the rate of compensatory evolution. It is shown that the effects of indirect compensation are very strong. We find that recombination does not slow down the rate of compensatory evolution as predicted by the classical model. Instead, compensatory substitutions may be relatively frequent, even if linkage between the focal interacting sites is loose, selection against deleterious mutations is strong, and mutation rate is low. We compare our theoretical results with data on RNA secondary structures from vertebrate introns.
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Affiliation(s)
- Junko Kusumi
- Department of Environmental Changes, Kyushu University, Fukuoka, Japan.
| | - Motoshi Ichinose
- Department of English and Multimedia Studies, Chikushi Jogakuen University, Dazaifu, Japan
| | - Masasuke Takefu
- Center for Comprehensive Community Medicine, Saga University, Saga, Japan
| | - Robert Piskol
- Department of Genetics, Stanford University, Stanford, USA
| | - Wolfgang Stephan
- Biocenter, Ludwig-Maximilian University Munich, Planegg, Germany
| | - Masaru Iizuka
- Division of Mathematics, Kyushu Dental University, Kitakyushu, Japan
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6
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Mao Y, Li Q, Zhang Y, Zhang J, Wei G, Tao S. Genome-wide analysis of selective constraints on high stability regions of mRNA reveals multiple compensatory mutations in Escherichia coli. PLoS One 2013; 8:e73299. [PMID: 24086278 PMCID: PMC3785496 DOI: 10.1371/journal.pone.0073299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 07/18/2013] [Indexed: 12/27/2022] Open
Abstract
Message RNA (mRNA) carries a large number of local secondary structures, with structural stability to participate in the regulations of gene expression. A worthy question is how the local structural stability is maintained under the constraint that multiple selective pressures are imposed on mRNA local regions. Here, we performed the first genome-wide study of natural selection operating on high structural stability regions (HSRs) of mRNAs in Escherichia coli. We found that HSR tends to adjust the folded conformation to reduce the harm of mutations, showing a high level of mutational robustness. Moreover, guanine preference in HSR was observed, supporting the hypothesis that the selective constraint for high structural stability may partly account for the high percentage of G content in Escherichia coli genome. Notably, we found a substantially reduced synonymous substitution rate in HSRs compared with that in their adjacent regions. Surprisingly and interestingly, the non-key sites in HSRs, which have slight effect on structural stability, have synonymous substitution rate equivalent to background regions. To explain this result, we identified compensatory mutations in HSRs based on structural stability, and found that a considerable number of synonymous mutations occur to restore the structural stability decreased heavily by the mutations on key sites. Overall, these results suggest a significant role of local structural stability as a selective force operating on mRNA, which furthers our understanding of the constraints imposed on protein-coding RNAs.
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Affiliation(s)
- Yuanhui Mao
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China
| | - Qian Li
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China
| | - Yinwen Zhang
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China
| | - Junjie Zhang
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China
| | - Gehong Wei
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail: (GW); (ST)
| | - Shiheng Tao
- College of Life Sciences and State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling, Shaanxi, China
- Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, China
- * E-mail: (GW); (ST)
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Sabarinathan R, Tafer H, Seemann SE, Hofacker IL, Stadler PF, Gorodkin J. RNAsnp: efficient detection of local RNA secondary structure changes induced by SNPs. Hum Mutat 2013; 34:546-56. [PMID: 23315997 PMCID: PMC3708107 DOI: 10.1002/humu.22273] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 12/18/2012] [Indexed: 02/05/2023]
Abstract
Structural characteristics are essential for the functioning of many noncoding RNAs and cis-regulatory elements of mRNAs. SNPs may disrupt these structures, interfere with their molecular function, and hence cause a phenotypic effect. RNA folding algorithms can provide detailed insights into structural effects of SNPs. The global measures employed so far suffer from limited accuracy of folding programs on large RNAs and are computationally too demanding for genome-wide applications. Here, we present a strategy that focuses on the local regions of maximal structural change between mutant and wild-type. These local regions are approximated in a “screening mode” that is intended for genome-wide applications. Furthermore, localized regions are identified as those with maximal discrepancy. The mutation effects are quantified in terms of empirical P values. To this end, the RNAsnp software uses extensive precomputed tables of the distribution of SNP effects as function of length and GC content. RNAsnp thus achieves both a noise reduction and speed-up of several orders of magnitude over shuffling-based approaches. On a data set comprising 501 SNPs associated with human-inherited diseases, we predict 54 to have significant local structural effect in the untranslated region of mRNAs. RNAsnp is available at http://rth.dk/resources/rnasnp.
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Will S, Siebauer MF, Heyne S, Engelhardt J, Stadler PF, Reiche K, Backofen R. LocARNAscan: Incorporating thermodynamic stability in sequence and structure-based RNA homology search. Algorithms Mol Biol 2013; 8:14. [PMID: 23601347 PMCID: PMC3716875 DOI: 10.1186/1748-7188-8-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 03/28/2013] [Indexed: 12/15/2022] Open
Abstract
Background The search for distant homologs has become an import issue in genome annotation. A particular difficulty is posed by divergent homologs that have lost recognizable sequence similarity. This same problem also arises in the recognition of novel members of large classes of RNAs such as snoRNAs or microRNAs that consist of families unrelated by common descent. Current homology search tools for structured RNAs are either based entirely on sequence similarity (such as blast or hmmer) or combine sequence and secondary structure. The most prominent example of the latter class of tools is Infernal. Alternatives are descriptor-based methods. In most practical applications published to-date, however, the information contained in covariance models or manually prescribed search patterns is dominated by sequence information. Here we ask two related questions: (1) Is secondary structure alone informative for homology search and the detection of novel members of RNA classes? (2) To what extent is the thermodynamic propensity of the target sequence to fold into the correct secondary structure helpful for this task? Results Sequence-structure alignment can be used as an alternative search strategy. In this scenario, the query consists of a base pairing probability matrix, which can be derived either from a single sequence or from a multiple alignment representing a set of known representatives. Sequence information can be optionally added to the query. The target sequence is pre-processed to obtain local base pairing probabilities. As a search engine we devised a semi-global scanning variant of LocARNA’s algorithm for sequence-structure alignment. The LocARNAscan tool is optimized for speed and low memory consumption. In benchmarking experiments on artificial data we observe that the inclusion of thermodynamic stability is helpful, albeit only in a regime of extremely low sequence information in the query. We observe, furthermore, that the sensitivity is bounded in particular by the limited accuracy of the predicted local structures of the target sequence. Conclusions Although we demonstrate that a purely structure-based homology search is feasible in principle, it is unlikely to outperform tools such as Infernal in most application scenarios, where a substantial amount of sequence information is typically available. The LocARNAscan approach will profit, however, from high throughput methods to determine RNA secondary structure. In transcriptome-wide applications, such methods will provide accurate structure annotations on the target side. Availability Source code of the free software LocARNAscan 1.0 and supplementary data are available at
http://www.bioinf.uni-leipzig.de/Software/LocARNAscan.
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Ichinose M, Iizuka M, Kusumi J, Takefu M. Models of compensatory molecular evolution: Effects of back mutation. J Theor Biol 2013; 323:1-10. [DOI: 10.1016/j.jtbi.2013.01.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 01/10/2013] [Accepted: 01/13/2013] [Indexed: 01/15/2023]
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10
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Piskol R, Stephan W. The role of the effective population size in compensatory evolution. Genome Biol Evol 2011; 3:528-38. [PMID: 21680889 PMCID: PMC3140890 DOI: 10.1093/gbe/evr057] [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] [Indexed: 12/17/2022] Open
Abstract
The impact of the effective population size (Ne) on the efficacy of selection has been the focus of many theoretical and empirical studies over the recent years. Yet, the effect of Ne on evolution under epistatic fitness interactions is not well understood. In this study, we compare selective constraints at independently evolving (unpaired) and coevolving (paired) sites in orthologous transfer RNAs (tRNA molecules for vertebrate and drosophilid species pairs of different Ne. We show that patterns of nucleotide variation for the two classes of sites are explained well by Kimura's one- and two-locus models of sequence evolution under mutational pressure. We find that constraints in orthologous tRNAs increase with increasing Ne of the investigated species pair. Thereby, the effect of Ne on the efficacy of selection is stronger at unpaired sites than at paired sites. Furthermore, we identify a “core” set of tRNAs with high structural similarity to tRNAs from all major kingdoms of life and a “peripheral” set with lower similarity. We observe that tRNAs in the former set are subject to higher constraints and less prone to the effect of Ne, whereas constraints in tRNAs of the latter set show a large influence of Ne. Finally, we are able to demonstrate that constraints are relaxed in X-linked drosophilid tRNAs compared with autosomal tRNAs and suggest that Ne is responsible for this difference. The observed effects of Ne are consistent with the hypothesis that evolution of most tRNAs is governed by slightly to moderately deleterious mutations (i.e., |Nes| ≤ 5).
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Affiliation(s)
- Robert Piskol
- Section of Evolutionary Biology, Ludwig-Maximilian University, Munich, Germany.
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