1
|
Hoh C, Salzberg SL. Discovering Intron Gain Events in Humans through Large-Scale Evolutionary Comparisons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.02.592247. [PMID: 38746259 PMCID: PMC11092651 DOI: 10.1101/2024.05.02.592247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The rapid growth in the number of sequenced genomes makes it possible to search for the appearance of entirely new introns in the human lineage. In this study, we compared the genomic sequences for 19,120 human protein-coding genes to a collection of 3493 vertebrate genomes, mapping the patterns of intron alignments onto a phylogenetic tree. This mapping allowed us to trace many intron gain events to precise locations in the tree, corresponding to distinct points in evolutionary history. We discovered 584 intron gain events, all of them relatively recent, in 514 distinct human genes. Among these events, we explored the hypothesis that intronization was the mechanism responsible for intron gain. Intronization events were identified by locating instances where human introns correspond to exonic sequences in homologous vertebrate genes. Although apparently rare, we found three compelling cases of intronization, and for each of those we compared the human protein sequence and structure to homologous genes that lack the introns.
Collapse
Affiliation(s)
- Celine Hoh
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
- Center for Computational Biology, Johns Hopkins University, Baltimore, MD 21211, USA
| | - Steven L Salzberg
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
- Center for Computational Biology, Johns Hopkins University, Baltimore, MD 21211, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21211, USA
- Department of Biostatistics, Johns Hopkins University, Baltimore, MD 21205, USA
| |
Collapse
|
2
|
Ares M, Igel H, Katzman S, Donohue JP. Intron-lariat spliceosomes convert lariats to true circles: implications for intron transposition. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.586863. [PMID: 38585890 PMCID: PMC10996645 DOI: 10.1101/2024.03.26.586863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Rare, full length circular intron RNAs distinct from lariats have been reported in several species, but their biogenesis is not understood. We envision and test a hypothesis for their formation using Saccharomyces cerevisiae, documenting full length and novel processed circular RNAs from multiple introns. Evidence implicates a previously undescribed catalytic activity of the intron-lariat spliceosome (ILS) in which the 3'-OH of the lariat tail (with optional trimming and adenylation by the nuclear 3' processing machinery) attacks the branch, joining the intron 3' end to the 5' splice site in a 3'-5' linked circle. Human U2 and U12 spliceosomes produce analogous full length and processed circles. Post-splicing catalytic activity of the spliceosome may promote intron transposition during eukaryotic genome evolution.
Collapse
Affiliation(s)
- Manuel Ares
- Center for Molecular Biology of RNA, University of California, Santa Cruz
- Genomics Institute, Santa Cruz, CA 95064 USA
| | - Haller Igel
- Center for Molecular Biology of RNA, University of California, Santa Cruz
| | - Sol Katzman
- Center for Molecular Biology of RNA, University of California, Santa Cruz
- Genomics Institute, Santa Cruz, CA 95064 USA
| | - John P. Donohue
- Center for Molecular Biology of RNA, University of California, Santa Cruz
| |
Collapse
|
3
|
Wu Y, Zhang L, Zeng XC, Shi W. Intronic Number Polymorphism in the Genes Encoding Potassium Channel Specific Venom Toxins from Scorpion. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422110126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
4
|
Schäfer GG, Grebe LJ, Schinkel R, Lieb B. The Evolution of Hemocyanin Genes in Caenogastropoda: Gene Duplications and Intron Accumulation in Highly Diverse Gastropods. J Mol Evol 2021; 89:639-655. [PMID: 34757470 PMCID: PMC8599328 DOI: 10.1007/s00239-021-10036-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 10/15/2021] [Indexed: 11/30/2022]
Abstract
Hemocyanin is the oxygen transport protein of most molluscs and represents an important physiological factor that has to be well-adapted to their environments because of the strong influences of abiotic factors on its oxygen affinity. Multiple independent gene duplications and intron gains have been reported for hemocyanin genes of Tectipleura (Heterobranchia) and the caenogastropod species Pomacea canaliculata, which contrast with the uniform gene architectures of hemocyanins in Vetigastropoda. The goal of this study was to analyze hemocyanin gene evolution within the diverse group of Caenogastropoda in more detail. Our findings reveal multiple gene duplications and intron gains and imply that these represent general features of Apogastropoda hemocyanins. Whereas hemocyanin exon–intron structures are identical within different Tectipleura lineages, they differ strongly within Caenogastropoda among phylogenetic groups as well as between paralogous hemocyanin genes of the same species. Thus, intron accumulation took place more gradually within Caenogastropoda but finally led to a similar consequence, namely, a multitude of introns. Since both phenomena occurred independently within Heterobranchia and Caenogastropoda, the results support the hypothesis that introns may contribute to adaptive radiation by offering new opportunities for genetic variability (multiple paralogs that may evolve differently) and regulation (multiple introns). Our study indicates that adaptation of hemocyanin genes may be one of several factors that contributed to the evolution of the large diversity of Apogastropoda. While questions remain, this hypothesis is presented as a starting point for the further study of hemocyanin genes and possible correlations between hemocyanin diversity and adaptive radiation.
Collapse
Affiliation(s)
- Gabriela Giannina Schäfer
- Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Johann-Joachim-Becher-Weg 7, 55128, Mainz, Germany
| | - Lukas Jörg Grebe
- Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Johann-Joachim-Becher-Weg 7, 55128, Mainz, Germany
| | - Robin Schinkel
- Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Johann-Joachim-Becher-Weg 7, 55128, Mainz, Germany
| | - Bernhard Lieb
- Institute of Molecular Physiology, Johannes Gutenberg-University of Mainz, Johann-Joachim-Becher-Weg 7, 55128, Mainz, Germany.
| |
Collapse
|
5
|
Internally Symmetrical Stwintrons and Related Canonical Introns in Hypoxylaceae Species. J Fungi (Basel) 2021; 7:jof7090710. [PMID: 34575748 PMCID: PMC8469720 DOI: 10.3390/jof7090710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 01/01/2023] Open
Abstract
Spliceosomal introns are pervasive in eukaryotes. Intron gains and losses have occurred throughout evolution, but the origin of new introns is unclear. Stwintrons are complex intervening sequences where one of the sequence elements (5′-donor, lariat branch point element or 3′-acceptor) necessary for excision of a U2 intron (external intron) is itself interrupted by a second (internal) U2 intron. In Hypoxylaceae, a family of endophytic fungi, we uncovered scores of donor-disrupted stwintrons with striking sequence similarity among themselves and also with canonical introns. Intron–exon structure comparisons suggest that these stwintrons have proliferated within diverging taxa but also give rise to proliferating canonical introns in some genomes. The proliferated (stw)introns have integrated seamlessly at novel gene positions. The recently proliferated (stw)introns appear to originate from a conserved ancestral stwintron characterised by terminal inverted repeats (45–55 nucleotides), a highly symmetrical structure that may allow the formation of a double-stranded intron RNA molecule. No short tandem duplications flank the putatively inserted intervening sequences, which excludes a DNA transposition-based mechanism of proliferation. It is tempting to suggest that this highly symmetrical structure may have a role in intron proliferation by (an)other mechanism(s).
Collapse
|
6
|
Zhang Y, Tian P, Duan G, Gao F, Schnabel G, Zhan J, Chen F. Histone H3 gene is not a suitable marker to distinguish Alternaria tenuissima from A. alternata affecting potato. PLoS One 2020; 15:e0231961. [PMID: 32324785 PMCID: PMC7179870 DOI: 10.1371/journal.pone.0231961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/03/2020] [Indexed: 11/21/2022] Open
Abstract
Potato Alternaria leaf blight is one of the economically most important disease in potato production worldwide. A recent study reported a quick method to distinguish main Alternaria pathogens A. tenuissima, A. alternata, and A. solani using partial histone H3 gene sequences. Using this method, our collection of 79 isolates from 8 provinces in China were presumably separated into A. tenussima and A. alternata. But in depth morphological and genetic analysis casted doubt on this identification. Culture morphologies of six presumed A. alternata isolates (PresA_alt) and six presumed A. tenuissima isolates (PresA_ten) were not significantly different. PresA_ten isolates also produced conidia in branched chains which supposed to be A. aternata. Phylogenetic analyses were conducted using internal transcribed spacer region (ITS) and five genes commonly used for species identification including glyceraldehyde-3-phosphate dehydrogenase (GPDH), translation elongation factor 1-alpha (TEF1), β-tubulin, plasma membrane ATPase (ATPase), and calmodulin genes. The results showed that GPDH and TEF1 sequences of PresA_alt and PresA_ten isolates were identical. The 12 isolates did not cluster by presumed species neither by individual or concatenated sequence comparisons. The phylogeny–trait association analysis confirmed that the two group isolates were undistinguishable by those molecular markers. Analysis of histone H3 gene sequences revealed variable intron sequences between PresA_ten and PresA_alt isolates, but the amino acid sequences were identical. Our results indicate that the previously published method to distinguish Alternaria species based on histone H3 gene sequence variation is inaccurate and that the prevalence of A. tenuissima isolates in China was likely overestimated.
Collapse
Affiliation(s)
- Yue Zhang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Peiyu Tian
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guohua Duan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Fangluan Gao
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guido Schnabel
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC, United States of America
| | - Jiasui Zhan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- * E-mail: (FC); (JZ)
| | - Fengping Chen
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
- * E-mail: (FC); (JZ)
| |
Collapse
|
7
|
Frumkin I, Yofe I, Bar-Ziv R, Gurvich Y, Lu YY, Voichek Y, Towers R, Schirman D, Krebber H, Pilpel Y. Evolution of intron splicing towards optimized gene expression is based on various Cis- and Trans-molecular mechanisms. PLoS Biol 2019; 17:e3000423. [PMID: 31442222 PMCID: PMC6728054 DOI: 10.1371/journal.pbio.3000423] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 09/05/2019] [Accepted: 08/08/2019] [Indexed: 01/09/2023] Open
Abstract
Splicing expands, reshapes, and regulates the transcriptome of eukaryotic organisms. Despite its importance, key questions remain unanswered, including the following: Can splicing evolve when organisms adapt to new challenges? How does evolution optimize inefficiency of introns’ splicing and of the splicing machinery? To explore these questions, we evolved yeast cells that were engineered to contain an inefficiently spliced intron inside a gene whose protein product was under selection for an increased expression level. We identified a combination of mutations in Cis (within the gene of interest) and in Trans (in mRNA-maturation machinery). Surprisingly, the mutations in Cis resided outside of known intronic functional sites and improved the intron’s splicing efficiency potentially by easing tight mRNA structures. One of these mutations hampered a protein’s domain that was not under selection, demonstrating the evolutionary flexibility of multi-domain proteins as one domain functionality was improved at the expense of the other domain. The Trans adaptations resided in two proteins, Npl3 and Gbp2, that bind pre-mRNAs and are central to their maturation. Interestingly, these mutations either increased or decreased the affinity of these proteins to mRNA, presumably allowing faster spliceosome recruitment or increased time before degradation of the pre-mRNAs, respectively. Altogether, our work reveals various mechanistic pathways toward optimizations of intron splicing to ultimately adapt gene expression patterns to novel demands. An experimental evolution study involving an inefficiently spliced intron reveals that the splicing machinery, introns, and RNA quality control factors evolve in Cis and in Trans when cells optimize their transcriptome to new challenges.
Collapse
Affiliation(s)
- Idan Frumkin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (IF); (YP)
| | - Ido Yofe
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yonat Gurvich
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yen-Yun Lu
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
| | - Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ruth Towers
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dvir Schirman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Heike Krebber
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
| | - Yitzhak Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- * E-mail: (IF); (YP)
| |
Collapse
|
8
|
Müller C, Lukas P, Lemke S, Hildebrandt JP. Hirudin and Decorsins of the North American Medicinal Leech Macrobdella decora: Gene Structure Reveals Homology to Hirudins and Hirudin-Like Factors of Eurasian Medicinal Leeches. J Parasitol 2019. [DOI: 10.1645/18-117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Christian Müller
- Animal Physiology and Biochemistry, Zoological Institute and Museum, University of Greifswald, 17489 Greifswald, Germany
| | - Phil Lukas
- Animal Physiology and Biochemistry, Zoological Institute and Museum, University of Greifswald, 17489 Greifswald, Germany
| | - Sarah Lemke
- Animal Physiology and Biochemistry, Zoological Institute and Museum, University of Greifswald, 17489 Greifswald, Germany
| | - Jan-Peter Hildebrandt
- Animal Physiology and Biochemistry, Zoological Institute and Museum, University of Greifswald, 17489 Greifswald, Germany
| |
Collapse
|
9
|
Intron-mediated regulation of β-tubulin genes expression affects the sensitivity to carbendazim in Fusarium graminearum. Curr Genet 2019; 65:1057-1069. [DOI: 10.1007/s00294-019-00960-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/13/2019] [Accepted: 03/26/2019] [Indexed: 12/20/2022]
|
10
|
Abstract
Boasting nearly 30,000 species, teleosts account for half of all extant vertebrates and approximately 98% of all ray-finned fish species (Actinopterygii). Teleosts are also the largest and most diverse group of vertebrates, exhibiting an astonishing level of morphological, physiological, and behavioral diversity. Previous studies had indicated that the teleost lineage has experienced an additional whole-genome duplication event. Recent comparative genomic analyses of teleosts and other bony vertebrates using spotted gar (a nonteleost ray-finned fish) and elephant shark (a cartilaginous fish) as outgroups have revealed several divergent features of teleost genomes. These include an accelerated evolutionary rate of protein-coding and nucleotide sequences, a higher rate of intron turnover, loss of many potential cis-regulatory elements and shorter conserved syntenic blocks. A combination of these divergent genomic features might have contributed to the evolution of the amazing phenotypic diversity and morphological innovations of teleosts.
Collapse
Affiliation(s)
- Vydianathan Ravi
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673; ,
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673; ,
| |
Collapse
|
11
|
Gotoh O. Modeling one thousand intron length distributions with fitild. Bioinformatics 2018; 34:3258-3264. [PMID: 29722882 PMCID: PMC6157073 DOI: 10.1093/bioinformatics/bty353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 05/01/2018] [Indexed: 11/13/2022] Open
Abstract
Motivation Intron length distribution (ILD) is a specific feature of a genome that exhibits extensive species-specific variation. Whereas ILD contributes to up to 30% of the total information content for intron recognition in some species, rendering it an important component of computational gene prediction, very few studies have been conducted to quantitatively characterize ILDs of various species. Results We developed a set of computer programs (fitild, compild, etc.) to build statistical models of ILDs and compare them with one another. Each ILD of more than 1000 genomes was fitted with fitild to a statistical model consisting of one, two, or three components of Frechet distributions. Several measures of distances between ILDs were calculated by compild. A theoretical model was presented to better understand the origin of the observed shape of an ILD. Availability and implementation The C++ source codes are available at https://github.com/ogotoh/fitild.git/. Supplementary information Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Osamu Gotoh
- Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tokyo Waterfront Bio-IT Research Building, Koto-ku, Tokyo, Japan.,Department of Intelligence Science and Technology, Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, Japan
| |
Collapse
|
12
|
Ma L, Cissé OH, Kovacs JA. A Molecular Window into the Biology and Epidemiology of Pneumocystis spp. Clin Microbiol Rev 2018; 31:e00009-18. [PMID: 29899010 PMCID: PMC6056843 DOI: 10.1128/cmr.00009-18] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pneumocystis, a unique atypical fungus with an elusive lifestyle, has had an important medical history. It came to prominence as an opportunistic pathogen that not only can cause life-threatening pneumonia in patients with HIV infection and other immunodeficiencies but also can colonize the lungs of healthy individuals from a very early age. The genus Pneumocystis includes a group of closely related but heterogeneous organisms that have a worldwide distribution, have been detected in multiple mammalian species, are highly host species specific, inhabit the lungs almost exclusively, and have never convincingly been cultured in vitro, making Pneumocystis a fascinating but difficult-to-study organism. Improved molecular biologic methodologies have opened a new window into the biology and epidemiology of Pneumocystis. Advances include an improved taxonomic classification, identification of an extremely reduced genome and concomitant inability to metabolize and grow independent of the host lungs, insights into its transmission mode, recognition of its widespread colonization in both immunocompetent and immunodeficient hosts, and utilization of strain variation to study drug resistance, epidemiology, and outbreaks of infection among transplant patients. This review summarizes these advances and also identifies some major questions and challenges that need to be addressed to better understand Pneumocystis biology and its relevance to clinical care.
Collapse
Affiliation(s)
- Liang Ma
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
| | - Ousmane H Cissé
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
| | - Joseph A Kovacs
- Critical Care Medicine Department, NIH Clinical Center, Bethesda, Maryland, USA
| |
Collapse
|
13
|
Lokits AD, Indrischek H, Meiler J, Hamm HE, Stadler PF. Tracing the evolution of the heterotrimeric G protein α subunit in Metazoa. BMC Evol Biol 2018; 18:51. [PMID: 29642851 PMCID: PMC5896119 DOI: 10.1186/s12862-018-1147-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 03/06/2018] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Heterotrimeric G proteins are fundamental signaling proteins composed of three subunits, Gα and a Gβγ dimer. The role of Gα as a molecular switch is critical for transmitting and amplifying intracellular signaling cascades initiated by an activated G protein Coupled Receptor (GPCR). Despite their biochemical and therapeutic importance, the study of G protein evolution has been limited to the scope of a few model organisms. Furthermore, of the five primary Gα subfamilies, the underlying gene structure of only two families has been thoroughly investigated outside of Mammalia evolution. Therefore our understanding of Gα emergence and evolution across phylogeny remains incomplete. RESULTS We have computationally identified the presence and absence of every Gα gene (GNA-) across all major branches of Deuterostomia and evaluated the conservation of the underlying exon-intron structures across these phylogenetic groups. We provide evidence of mutually exclusive exon inclusion through alternative splicing in specific lineages. Variations of splice site conservation and isoforms were found for several paralogs which coincide with conserved, putative motifs of DNA-/RNA-binding proteins. In addition to our curated gene annotations, within Primates, we identified 15 retrotranspositions, many of which have undergone pseudogenization. Most importantly, we find numerous deviations from previous findings regarding the presence and absence of individual GNA- genes, nuanced differences in phyla-specific gene copy numbers, novel paralog duplications and subsequent intron gain and loss events. CONCLUSIONS Our curated annotations allow us to draw more accurate inferences regarding the emergence of all Gα family members across Metazoa and to present a new, updated theory of Gα evolution. Leveraging this, our results are critical for gaining new insights into the co-evolution of the Gα subunit and its many protein binding partners, especially therapeutically relevant G protein - GPCR signaling pathways which radiated in Vertebrata evolution.
Collapse
Affiliation(s)
- A. D. Lokits
- 0000 0001 2264 7217grid.152326.1Neuroscience Program, Vanderbilt University, Nashville, TN USA ,0000 0001 2264 7217grid.152326.1Center for Structural Biology, Vanderbilt University, Nashville, TN USA
| | - H. Indrischek
- 0000 0001 2230 9752grid.9647.cBioinformatics Group, Department of Computer Science, Leipzig University, Leipzig, Germany ,0000 0001 2230 9752grid.9647.cComputational EvoDevo Group, Bioinformatics Department, Leipzig University, Leipzig, Germany
| | - J. Meiler
- 0000 0001 2264 7217grid.152326.1Center for Structural Biology, Vanderbilt University, Nashville, TN USA ,0000 0001 2264 7217grid.152326.1Chemistry Department, Vanderbilt University, Nashville, TN USA
| | - H. E. Hamm
- 0000 0004 1936 9916grid.412807.8Pharmacology Department, Vanderbilt University Medical Center, Nashville, TN USA
| | - P. F. Stadler
- 0000 0001 2230 9752grid.9647.cBioinformatics Group, Department of Computer Science, Leipzig University, Leipzig, Germany ,0000 0001 0674 042Xgrid.5254.6Center for non-coding RNA in Technology and Health, University of Copenhagen, Frederiksberg C, Denmark ,0000 0001 2286 1424grid.10420.37Institute for Theoretical Chemistry, University of Vienna, Wien, Austria ,0000 0001 2230 9752grid.9647.cIZBI-Interdisciplinary Center for Bioinformatics and LIFE-Leipzig Research Center for Civilization Diseases and Competence Center for Scalable Data Services and Solutions, University Leipzig, Leipzig, Germany ,grid.419532.8Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany ,0000 0001 1941 1940grid.209665.eSanta Fe Institute, Santa Fe, NM USA
| |
Collapse
|
14
|
Abstract
The presence of intervening sequences, termed introns, is a defining characteristic of eukaryotic nuclear genomes. Once transcribed into pre-mRNA, these introns must be removed within the spliceosome before export of the processed mRNA to the cytoplasm, where it is translated into protein. Although intron loss has been demonstrated experimentally, several mysteries remain regarding the origin and propagation of introns. Indeed, documented evidence of gain of an intron has only been suggested by phylogenetic analyses. We report the use of a strategy that detects selected intron gain and loss events. We have experimentally verified, to our knowledge, the first demonstrations of intron transposition in any organism. From our screen, we detected two separate intron gain events characterized by the perfect transposition of a reporter intron into the yeast genes RPL8B and ADH2, respectively. We show that the newly acquired introns are able to be removed from their respective pre-mRNAs by the spliceosome. Additionally, the novel allele, RPL8Bint, is functional when overexpressed within the genome in a strain lacking the Rpl8 paralogue RPL8A, demonstrating that the gene targeted for intronogenesis is functional.
Collapse
|
15
|
ZHANG LI, KANG HAN, JIN SHAN, ZENG QINGTAO, YANG YONG. Hsp27 gene in Drosophila ananassae subgroup was split by a recently acquired intron. J Genet 2016; 95:257-62. [DOI: 10.1007/s12041-016-0629-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
16
|
Kumar A. Bayesian phylogeny analysis of vertebrate serpins illustrates evolutionary conservation of the intron and indels based six groups classification system from lampreys for ∼500 MY. PeerJ 2015; 3:e1026. [PMID: 26157611 PMCID: PMC4476131 DOI: 10.7717/peerj.1026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 05/26/2015] [Indexed: 11/20/2022] Open
Abstract
The serpin superfamily is characterized by proteins that fold into a conserved tertiary structure and exploits a sophisticated and irreversible suicide-mechanism of inhibition. Vertebrate serpins are classified into six groups (V1-V6), based on three independent biological features-genomic organization, diagnostic amino acid sites and rare indels. However, this classification system was based on the limited number of mammalian genomes available. In this study, several non-mammalian genomes are used to validate this classification system using the powerful Bayesian phylogenetic method. This method supports the intron and indel based vertebrate classification and proves that serpins have been maintained from lampreys to humans for about 500 MY. Lampreys have fewer than 10 serpins, which expand into 36 serpins in humans. The two expanding groups V1 and V2 have SERPINB1/SERPINB6 and SERPINA8/SERPIND1 as the ancestral serpins, respectively. Large clusters of serpins are formed by local duplications of these serpins in tetrapod genomes. Interestingly, the ancestral HCII/SERPIND1 locus (nested within PIK4CA) possesses group V4 serpin (A2APL1, homolog of α 2-AP/SERPINF2) of lampreys; hence, pointing to the fact that group V4 might have originated from group V2. Additionally in this study, details of the phylogenetic history and genomic characteristics of vertebrate serpins are revisited.
Collapse
Affiliation(s)
- Abhishek Kumar
- Department of Genetics & Molecular Biology in Botany, Institute of Botany, Christian-Albrechts-University at Kiel, Kiel, Germany
| |
Collapse
|
17
|
Collemare J, Beenen HG, Crous PW, de Wit PJGM, van der Burgt A. Novel Introner-Like Elements in fungi Are Involved in Parallel Gains of Spliceosomal Introns. PLoS One 2015; 10:e0129302. [PMID: 26046656 PMCID: PMC4457414 DOI: 10.1371/journal.pone.0129302] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/08/2015] [Indexed: 01/08/2023] Open
Abstract
Spliceosomal introns are key components of the eukaryotic gene structure. Although they contributed to the emergence of eukaryotes, their origin remains elusive. In fungi, they might originate from the multiplication of invasive introns named Introner-Like Elements (ILEs). However, so far ILEs have been observed in six fungal species only, including Fulvia fulva and Dothistroma septosporum (Dothideomycetes), arguing against ILE insertion as a general mechanism for intron gain. Here, we identified novel ILEs in eight additional fungal species that are phylogenetically related to F. fulva and D. septosporum using PCR amplification with primers derived from previously identified ILEs. The ILE content appeared unique to each species, suggesting independent multiplication events. Interestingly, we identified four genes each containing two gained ILEs. By analysing intron positions in orthologues of these four genes in Ascomycota, we found that three ILEs had inserted within a 15 bp window that contains regular spliceosomal introns in other fungal species. These three positions are not the result of intron sliding because ILEs are newly gained introns. Furthermore, the alternative hypothesis of an inferred ancestral gain followed by independent losses contradicts the observed degeneration of ILEs. These observations clearly indicate three parallel intron gains in four genes that were randomly identified. Our findings suggest that parallel intron gain is a phenomenon that has been highly underestimated in ILE-containing fungi, and likely in the whole fungal kingdom.
Collapse
Affiliation(s)
- Jérôme Collemare
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Present address: UMR1345 IRHS-INRA, Beaucouzé, France
- * E-mail:
| | - Henriek G. Beenen
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Present address: Dyadic, Wageningen, The Netherlands
| | - Pedro W. Crous
- Evolutionary Phytopathology, CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands
| | | | - Ate van der Burgt
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Present address: Dyadic, Wageningen, The Netherlands
| |
Collapse
|
18
|
Piégu B, Bire S, Arensburger P, Bigot Y. A survey of transposable element classification systems--a call for a fundamental update to meet the challenge of their diversity and complexity. Mol Phylogenet Evol 2015; 86:90-109. [PMID: 25797922 DOI: 10.1016/j.ympev.2015.03.009] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/11/2015] [Accepted: 03/12/2015] [Indexed: 10/25/2022]
Abstract
The increase of publicly available sequencing data has allowed for rapid progress in our understanding of genome composition. As new information becomes available we should constantly be updating and reanalyzing existing and newly acquired data. In this report we focus on transposable elements (TEs) which make up a significant portion of nearly all sequenced genomes. Our ability to accurately identify and classify these sequences is critical to understanding their impact on host genomes. At the same time, as we demonstrate in this report, problems with existing classification schemes have led to significant misunderstandings of the evolution of both TE sequences and their host genomes. In a pioneering publication Finnegan (1989) proposed classifying all TE sequences into two classes based on transposition mechanisms and structural features: the retrotransposons (class I) and the DNA transposons (class II). We have retraced how ideas regarding TE classification and annotation in both prokaryotic and eukaryotic scientific communities have changed over time. This has led us to observe that: (1) a number of TEs have convergent structural features and/or transposition mechanisms that have led to misleading conclusions regarding their classification, (2) the evolution of TEs is similar to that of viruses by having several unrelated origins, (3) there might be at least 8 classes and 12 orders of TEs including 10 novel orders. In an effort to address these classification issues we propose: (1) the outline of a universal TE classification, (2) a set of methods and classification rules that could be used by all scientific communities involved in the study of TEs, and (3) a 5-year schedule for the establishment of an International Committee for Taxonomy of Transposable Elements (ICTTE).
Collapse
Affiliation(s)
- Benoît Piégu
- UMR INRA-CNRS 7247, PRC, Centre INRA de Nouzilly, 37380 Nouzilly, France
| | - Solenne Bire
- UMR INRA-CNRS 7247, PRC, Centre INRA de Nouzilly, 37380 Nouzilly, France; Institute of Biotechnology, University of Lausanne, Center for Biotechnology UNIL-EPFL, 1015 Lausanne, Switzerland
| | - Peter Arensburger
- UMR INRA-CNRS 7247, PRC, Centre INRA de Nouzilly, 37380 Nouzilly, France; Biological Sciences Department, California State Polytechnic University, Pomona, CA 91768, United States.
| | - Yves Bigot
- UMR INRA-CNRS 7247, PRC, Centre INRA de Nouzilly, 37380 Nouzilly, France.
| |
Collapse
|
19
|
Wang H, Devos KM, Bennetzen JL. Recurrent loss of specific introns during angiosperm evolution. PLoS Genet 2014; 10:e1004843. [PMID: 25474210 PMCID: PMC4256211 DOI: 10.1371/journal.pgen.1004843] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 10/22/2014] [Indexed: 11/18/2022] Open
Abstract
Numerous instances of presence/absence variations for introns have been documented in eukaryotes, and some cases of recurrent loss of the same intron have been suggested. However, there has been no comprehensive or phylogenetically deep analysis of recurrent intron loss. Of 883 cases of intron presence/absence variation that we detected in five sequenced grass genomes, 93 were confirmed as recurrent losses and the rest could be explained by single losses (652) or single gains (118). No case of recurrent intron gain was observed. Deep phylogenetic analysis often indicated that apparent intron gains were actually numerous independent losses of the same intron. Recurrent loss exhibited extreme non-randomness, in that some introns were removed independently in many lineages. The two larger genomes, maize and sorghum, were found to have a higher rate of both recurrent loss and overall loss and/or gain than foxtail millet, rice or Brachypodium. Adjacent introns and small introns were found to be preferentially lost. Intron loss genes exhibited a high frequency of germ line or early embryogenesis expression. In addition, flanking exon A+T-richness and intron TG/CG ratios were higher in retained introns. This last result suggests that epigenetic status, as evidenced by a loss of methylated CG dinucleotides, may play a role in the process of intron loss. This study provides the first comprehensive analysis of recurrent intron loss, makes a series of novel findings on the patterns of recurrent intron loss during the evolution of the grass family, and provides insight into the molecular mechanism(s) underlying intron loss. The spliceosomal introns are nucleotide sequences that interrupt coding regions of eukaryotic genes and are removed by RNA splicing after transcription. Recent studies have reported several examples of possible recurrent intron loss or gain, i.e., introns that are independently removed from or inserted into the identical sites more than once in an investigated phylogeny. However, the frequency, evolutionary patterns or other characteristics of recurrent intron turnover remain unknown. We provide results for the first comprehensive analysis of recurrent intron turnover within a plant family and show that recurrent intron loss represents a considerable portion of all intron losses identified and intron loss events far outnumber intron gain events. We also demonstrate that recurrent intron loss is non-random, affecting only a small number of introns that are repeatedly lost, and that different lineages show significantly different rates of intron loss. Our results suggest a possible role of DNA methylation in the process of intron loss. Moreover, this study provides strong support for the model of intron loss by reverse transcriptase mediated conversion of genes by their processed mRNA transcripts.
Collapse
Affiliation(s)
- Hao Wang
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Katrien M. Devos
- Department of Crop and Soil Sciences, and Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America
| | - Jeffrey L. Bennetzen
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
- Germplasm Bank of Wild Species in Southwestern China, Kunming Institute of Botany, Kunming, Yunnan, P.R. China
- * E-mail:
| |
Collapse
|
20
|
Kumar A, Bhandari A, Goswami C. Surveying genetic variants and molecular phylogeny of cerebral cavernous malformation gene, CCM3/PDCD10. Biochem Biophys Res Commun 2014; 455:98-106. [DOI: 10.1016/j.bbrc.2014.10.105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 11/29/2022]
|
21
|
Verhelst B, Van de Peer Y, Rouzé P. The complex intron landscape and massive intron invasion in a picoeukaryote provides insights into intron evolution. Genome Biol Evol 2014; 5:2393-401. [PMID: 24273312 PMCID: PMC3879977 DOI: 10.1093/gbe/evt189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Genes in pieces and spliceosomal introns are a landmark of eukaryotes, with intron invasion usually assumed to have happened early on in evolution. Here, we analyze the intron landscape of Micromonas, a unicellular green alga in the Mamiellophyceae lineage, demonstrating the coexistence of several classes of introns and the occurrence of recent massive intron invasion. This study focuses on two strains, CCMP1545 and RCC299, and their related individuals from ocean samplings, showing that they not only harbor different classes of introns depending on their location in the genome, as for other Mamiellophyceae, but also uniquely carry several classes of repeat introns. These introns, dubbed introner elements (IEs), are found at novel positions in genes and have conserved sequences, contrary to canonical introns. This IE invasion has a huge impact on the genome, doubling the number of introns in the CCMP1545 strain. We hypothesize that each IE class originated from a single ancestral IE that has been colonizing the genome after strain divergence by inserting copies of itself into genes by intron transposition, likely involving reverse splicing. Along with similar cases recently observed in other organisms, our observations in Micromonas strains shed a new light on the evolution of introns, suggesting that intron gain is more widespread than previously thought.
Collapse
Affiliation(s)
- Bram Verhelst
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Belgium
| | | | | |
Collapse
|
22
|
Kumar A, Bhandari A, Sarde SJ, Goswami C. Genetic variants and evolutionary analyses of heparin cofactor II. Immunobiology 2014; 219:713-28. [PMID: 24950623 DOI: 10.1016/j.imbio.2014.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 04/13/2014] [Accepted: 05/19/2014] [Indexed: 11/25/2022]
Abstract
Heparin cofactor II (HCII) belongs to serpin superfamily and it acts as a thrombin inhibitor in the coagulation cascade, in a glycosaminoglycan-dependent pathway using the release of a sequestered hirudin-like N-terminal tail for interaction with thrombin. This serpin belongs to multiple member group V2 of vertebrate serpin classification. However, there is no comprehensive study illustrating the exact phylogenetic history of HCII, to date. Herein, we explored phylogenetic traits of HCII genes. Structures of HCII gene from selected ray-finned fishes and lamprey varied in exon I and II with insertions of novel introns of which one in core domain for ray-finned fishes in exon II at the position 241c. We found HCII remain nested in the largest intron of phosphatidylinositol (PI) 4-kinase (PIK4CA) gene (genetic variants of this gene cause schizophrenia) at the origin of vertebrates, dated about 500MY old. We found that sequence features such as two acidic repeats (AR1-II), GAG-binding helix-D, three serpin motifs and inhibitory reactive center loop (RCL) of HCII protein are highly conserved in 55 vertebrates analyzed. We identified 985 HCII variants by analysis of 1092 human genomes with top three variation classes belongs to SNPs (84.3%), insertion (7.1%) and deletion (5.0%). We identified 37 deleterious mutations in the human HCII protein and we have described these mutations in relation to HCII sequence-structure-function relationships. These understandings may have clinical and medical importance as well.
Collapse
Affiliation(s)
- Abhishek Kumar
- Department of Genetics & Molecular Biology in Botany, Institute of Botany, Christian-Albrechts-University at Kiel, Kiel, Germany.
| | - Anita Bhandari
- Molecular Physiology, Zoological Institute, Christian-Albrechts-University at Kiel, Kiel, Germany
| | - Sandeep J Sarde
- Department of Genetics & Molecular Biology in Botany, Institute of Botany, Christian-Albrechts-University at Kiel, Kiel, Germany; Master Program Agrigenomics, Christian-Albrechts-University at Kiel, Kiel, Germany
| | - Chandan Goswami
- National Institute of Science Education and Research, Bhubaneswar, Orissa, India
| |
Collapse
|
23
|
Zhang C, Gschwend AR, Ouyang Y, Long M. Evolution of gene structural complexity: an alternative-splicing-based model accounts for intron-containing retrogenes. PLANT PHYSIOLOGY 2014; 165:412-23. [PMID: 24520158 PMCID: PMC4012599 DOI: 10.1104/pp.113.231696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The structure of eukaryotic genes evolves extensively by intron loss or gain. Previous studies have revealed two models for gene structure evolution through the loss of introns: RNA-based gene conversion, dubbed the Fink model and retroposition model. However, retrogenes that experienced both intron loss and intron-retaining events have been ignored; evolutionary processes responsible for the variation in complex exon-intron structure were unknown. We detected hundreds of retroduplication-derived genes in human (Homo sapiens), fly (Drosophila melanogaster), rice (Oryza sativa), and Arabidopsis (Arabidopsis thaliana) and categorized them either as duplicated genes that have all introns lost or as duplicated genes that have at least lost one and retained one intron compared with the parental copy (intron-retaining [IR] type). Our new model attributes intron retention alternative splicing to the generation of these IR-type gene pairs. We presented 25 parental genes that have an intron retention isoform and have retained introns in the same locations in the IR-type duplicate genes, which directly support our hypothesis. Our alternative-splicing-based model in conjunction with the retroposition and Fink models can explain the IR-type gene observed. We discovered a greater percentage of IR-type genes in plants than in animals, which may be due to the abundance of intron retention cases in plants. Given the prevalence of intron retention in plants, this new model gives a support that plant genomes have very complex gene structures.
Collapse
|
24
|
Jagielska E, Płucienniczak A, Dąbrowska M, Dowierciał A, Rode W. Trichinella pseudospiralis vs. T. spiralis thymidylate synthase gene structure and T. pseudospiralis thymidylate synthase retrogene sequence. Parasit Vectors 2014; 7:175. [PMID: 24716800 PMCID: PMC4022200 DOI: 10.1186/1756-3305-7-175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 03/27/2014] [Indexed: 12/31/2022] Open
Abstract
Background Thymidylate synthase is a housekeeping gene, designated ancient due to its role in DNA synthesis and ubiquitous phyletic distribution. The genomic sequences were characterized coding for thymidylate synthase in two species of the genus Trichinella, an encapsulating T. spiralis and a non-encapsulating T. pseudospiralis. Methods Based on the sequence of parasitic nematode Trichinella spiralis thymidylate synthase cDNA, PCR techniques were employed. Results Each of the respective gene structures encompassed 6 exons and 5 introns located in conserved sites. Comparison with the corresponding gene structures of other eukaryotic species revealed lack of common introns that would be shared among selected fungi, nematodes, mammals and plants. The two deduced amino acid sequences were 96% identical. In addition to the thymidylate synthase gene, the intron-less retrocopy, i.e. a processed pseudogene, with sequence identical to the T. spiralis gene coding region, was found to be present within the T. pseudospiralis genome. This pseudogene, instead of the gene, was confirmed by RT-PCR to be expressed in the parasite muscle larvae. Conclusions Intron load, as well as distribution of exon and intron phases in thymidylate synthase genes from various sources, point against the theory of gene assembly by the primordial exon shuffling and support the theory of evolutionary late intron insertion into spliceosomal genes. Thymidylate synthase pseudogene expressed in T. pseudospiralis muscle larvae is designated a retrogene.
Collapse
Affiliation(s)
| | | | | | | | - Wojciech Rode
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warszawa, Poland.
| |
Collapse
|
25
|
Zeng XC, Liu Y, Shi W, Zhang L, Luo X, Nie Y, Yang Y. Genome-wide search and comparative genomic analysis of the trypsin inhibitor-like cysteine-rich domain-containing peptides. Peptides 2014; 53:106-14. [PMID: 23973966 DOI: 10.1016/j.peptides.2013.08.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/13/2013] [Accepted: 08/13/2013] [Indexed: 11/24/2022]
Abstract
It was shown that peptides containing trypsin inhibitor-like cysteine-rich (TIL) domain are able to inhibit proteinase activities, and thus play important roles in various biological processes, such as immune response and anticoagulation. However, only a limited number of the TIL peptides have been identified and characterized so far; and little has been known about the evolutionary relationships of the genes encoding the TIL peptides. BmKAPi is a TIL domain-containing peptide that was identified from Mesobuthus martensii Karsch. Here, we conducted genome-wide searches for new peptides that are homologous to BmKAPi or possess a cysteine pattern similar to that of BmKAPi. As a result, we identified a total of 80 different TIL peptides from 34 species of arthropods. We found that these peptides can be classified into seven evolutionarily distinct groups. Furthermore, we cloned the genomic sequence of BmKAPi; the genomic sequences of the majority of other TIL peptides were also identified from the GenBank database using bioinformatical approaches. Through phylogenetic and comparative genomic analysis, we found 26 cases of intron gain events occurred in the genes of the TIL peptides; however, no instances of intron loss were observed. Moreover, we found that alternative splicing contributes to the diversification of the TIL peptides. It is interesting to see that four genes of the TIL domain-containing peptides overlap in a DNA region located on the chromosome LG B15 of Bombus terretris. These data suggest that the evolution of the TIL peptide genes are dynamic, which was dominated by intron gain.
Collapse
Affiliation(s)
- Xian-Chun Zeng
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China.
| | - Yichen Liu
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| | - Wanxia Shi
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| | - Lei Zhang
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| | - Xuesong Luo
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| | - Yao Nie
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| | - Ye Yang
- State Key Laboratory of Biogeology and Environmental Geology & Department of Biological Science and Technology, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China
| |
Collapse
|
26
|
Pascual-Anaya J, D'Aniello S, Kuratani S, Garcia-Fernàndez J. Evolution of Hox gene clusters in deuterostomes. BMC DEVELOPMENTAL BIOLOGY 2013; 13:26. [PMID: 23819519 PMCID: PMC3707753 DOI: 10.1186/1471-213x-13-26] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 07/02/2013] [Indexed: 11/10/2022]
Abstract
Hox genes, with their similar roles in animals as evolutionarily distant as humans and flies, have fascinated biologists since their discovery nearly 30 years ago. During the last two decades, reports on Hox genes from a still growing number of eumetazoan species have increased our knowledge on the Hox gene contents of a wide range of animal groups. In this review, we summarize the current Hox inventory among deuterostomes, not only in the well-known teleosts and tetrapods, but also in the earlier vertebrate and invertebrate groups. We draw an updated picture of the ancestral repertoires of the different lineages, a sort of “genome Hox bar-code” for most clades. This scenario allows us to infer differential gene or cluster losses and gains that occurred during deuterostome evolution, which might be causally linked to the morphological changes that led to these widely diverse animal taxa. Finally, we focus on the challenging family of posterior Hox genes, which probably originated through independent tandem duplication events at the origin of each of the ambulacrarian, cephalochordate and vertebrate/urochordate lineages.
Collapse
|
27
|
Flipphi M, Fekete E, Ag N, Scazzocchio C, Karaffa L. Spliceosome twin introns in fungal nuclear transcripts. Fungal Genet Biol 2013; 57:48-57. [PMID: 23792080 DOI: 10.1016/j.fgb.2013.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 06/07/2013] [Accepted: 06/09/2013] [Indexed: 10/26/2022]
Abstract
The spliceosome is an RNA/protein complex, responsible for intron excision from eukaryotic nuclear transcripts. In bacteria, mitochondria and plastids, intron excision does not involve the spliceosome, but occurs through mechanisms dependent on intron RNA secondary and tertiary structure. For group II/III chloroplast introns, "twintrons" (introns within introns) have been described. The excision of the external intron, and thus proper RNA maturation, necessitates prior removal of the internal intron, which interrupts crucial sequences of the former. We have here predicted analogous instances of spliceosomal twintrons ("stwintrons") in filamentous fungi. In two specific cases, where the internal intron interrupts the donor of the external intron after the first or after the second nucleotide, respectively, we show that intermediates with the sequence predicted by the "stwintron" hypothesis, are produced in the splicing process. This implies that two successive rounds of RNA scanning by the spliceosome are necessary to produce the mature mRNA. The phylogenetic distributions of the stwintrons we have identified suggest that they derive from "late" events, subsequent to the appearance of the host intron. They may well not be limited to fungal nuclear transcripts, and their generation and eventual disappearance in the evolutionary process are relevant to hypotheses of intron origin and alternative splicing.
Collapse
Affiliation(s)
- Michel Flipphi
- Department of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, 4010 Debrecen, Hungary.
| | | | | | | | | |
Collapse
|
28
|
Collemare J, van der Burgt A, de Wit PJGM. At the origin of spliceosomal introns: Is multiplication of introner-like elements the main mechanism of intron gain in fungi? Commun Integr Biol 2013; 6:e23147. [PMID: 23750299 PMCID: PMC3609843 DOI: 10.4161/cib.23147] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The recent discovery of introner-like elements (ILEs) in six fungal species shed new light on the origin of regular spliceosomal introns (RSIs) and the mechanism of intron gains. These novel spliceosomal introns are found in hundreds of copies, are longer than RSIs and harbor stable predicted secondary structures. Yet, they are prone to degeneration in sequence and length to become undistinguishable from RSIs, suggesting that ILEs are predecessors of most RSIs. In most fungi, other near-identical introns were found duplicated in lower numbers in the same gene or in unrelated genes, indicating that intron duplication is a widespread phenomenon. However, ILEs are associated with the majority of intron gains, suggesting that the other types of duplication are of minor importance to the overall gains of introns. Our data support the hypothesis that ILEs’ multiplication corresponds to the main mechanism of intron gain in fungi.
Collapse
Affiliation(s)
- Jérôme Collemare
- Laboratory of Phytopathology; Wageningen University; Wageningen, The Netherlands
| | | | | |
Collapse
|
29
|
Whitehead MP, Hooley P, W Brown MR. Horizontal transfer of bacterial polyphosphate kinases to eukaryotes: implications for the ice age and land colonisation. BMC Res Notes 2013; 6:221. [PMID: 23738841 PMCID: PMC3680246 DOI: 10.1186/1756-0500-6-221] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 05/11/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Studies of online database(s) showed that convincing examples of eukaryote PPKs derived from bacteria type PPK1 and PPK2 enzymes are rare and currently confined to a few simple eukaryotes. These enzymes probably represent several separate horizontal transfer events. Retention of such sequences may be an advantage for tolerance to stresses such as desiccation or nutrient depletion for simple eukaryotes that lack more sophisticated adaptations available to multicellular organisms. We propose that the acquisition of encoding sequences for these enzymes by horizontal transfer enhanced the ability of early plants to colonise the land. The improved ability to sequester and release inorganic phosphate for carbon fixation by photosynthetic algae in the ocean may have accelerated or even triggered global glaciation events. There is some evidence for DNA sequences encoding PPKs in a wider range of eukaryotes, notably some invertebrates, though it is unclear that these represent functional genes.Polyphosphate (poly P) is found in all cells, carrying out a wide range of essential roles. Studied mainly in prokaryotes, the enzymes responsible for synthesis of poly P in eukaryotes (polyphosphate kinases PPKs) are not well understood. The best characterised enzyme from bacteria known to catalyse the formation of high molecular weight polyphosphate from ATP is PPK1 which shows some structural similarity to phospholipase D. A second bacterial PPK (PPK2) resembles thymidylate kinase. Recent reports have suggested a widespread distribution of these bacteria type enzymes in eukaryotes. RESULTS On - line databases show evidence for the presence of genes encoding PPK1 in only a limited number of eukaryotes. These include the photosynthetic eukaryotes Ostreococcus tauri, O. lucimarinus, Porphyra yezoensis, Cyanidioschyzon merolae and the moss Physcomitrella patens, as well as the amoeboid symbiont Capsaspora owczarzaki and the non-photosynthetic eukaryotes Dictyostelium (3 species), Polysphondylium pallidum and Thecamonas trahens. A second bacterial PPK (PPK2) is found in just two eukaryotes (O. tauri and the sea anemone Nematostella vectensis). There is some evidence for PPK1 and PPK2 encoding sequences in other eukaryotes but some of these may be artefacts of bacterial contamination of gene libraries. CONCLUSIONS Evidence for the possible origins of these eukaryote PPK1s and PPK2s and potential prokaryote donors via horizontal gene transfer is presented. The selective advantage of acquiring and maintaining a prokaryote PPK in a eukaryote is proposed to enhance stress tolerance in a changing environment related to the capture and metabolism of inorganic phosphate compounds. Bacterial PPKs may also have enhanced the abilities of marine phytoplankton to sequester phosphate, hence accelerating global carbon fixation.
Collapse
|
30
|
Zhu T, Niu DK. Mechanisms of intron loss and gain in the fission yeast Schizosaccharomyces. PLoS One 2013; 8:e61683. [PMID: 23613904 PMCID: PMC3629103 DOI: 10.1371/journal.pone.0061683] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/13/2013] [Indexed: 11/24/2022] Open
Abstract
The fission yeast, Schizosaccharomyces pombe, is an important model species with a low intron density. Previous studies showed extensive intron losses during its evolution. To test the models of intron loss and gain in fission yeasts, we conducted a comparative genomic analysis in four Schizosaccharomyces species. Both intronization and de-intronization were observed, although both were at a low frequency. A de-intronization event was caused by a degenerative mutation in the branch site. Four cases of imprecise intron losses were identified, indicating that genomic deletion is not a negligible mechanism of intron loss. Most intron losses were precise deletions of introns, and were significantly biased to the 3′ sides of genes. Adjacent introns tended to be lost simultaneously. These observations indicated that the main force shaping the exon-intron structures of fission yeasts was precise intron losses mediated by reverse transcriptase. We found two cases of intron gains caused by tandem genomic duplication, but failed to identify the mechanisms for the majority of the intron gain events observed. In addition, we found that intron-lost and intron-gained genes had certain similar features, such as similar Gene Ontology categories and expression levels.
Collapse
Affiliation(s)
- Tao Zhu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Deng-Ke Niu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, China
- * E-mail:
| |
Collapse
|
31
|
Zeng XC, Nie Y, Luo X, Wu S, Shi W, Zhang L, Liu Y, Cao H, Yang Y, Zhou J. Molecular and bioinformatical characterization of a novel superfamily of cysteine-rich peptides from arthropods. Peptides 2013; 41:45-58. [PMID: 23099316 DOI: 10.1016/j.peptides.2012.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/05/2012] [Accepted: 10/05/2012] [Indexed: 12/17/2022]
Abstract
The full-length cDNA sequences of two novel cysteine-rich peptides (referred to as HsVx1 and MmKTx1) were obtained from scorpions. The two peptides represent a novel class of cysteine-rich peptides with a unique cysteine pattern. The genomic sequence of HsVx1 is composed of three exons interrupted by two introns that are localized in the mature peptide encoding region and inserted in phase 1 and phase 2, respectively. Such a genomic organization markedly differs from those of other peptides from scorpions described previously. Genome-wide search for the orthologs of HsVx1 identified 59 novel cysteine-rich peptides from arthropods. These peptides share a consistent cysteine pattern with HsVx1. Genomic comparison revealed extensive intron length differences and intronic number and position polymorphisms among the genes of these peptides. Further analysis identified 30 cases of intron sliding, 1 case of intron gain and 22 cases of intron loss occurred with the genes of the HsVx1 and HsVx1-like peptides. It is interesting to see that three HsVx1-like peptides XP_001658928, XP_001658929 and XP_001658930 were derived from a single gene (XP gene): the former two were generated from alternative splicing; the third one was encoded by a DNA region in the reverse complementary strand of the third intron of the XP gene. These findings strongly suggest that the genes of these cysteine-rich peptides were evolved by intron sliding, intron gain/loss, gene recombination and alternative splicing events in response to selective forces without changing their cysteine pattern. The evolution of these genes is dominated by intron sliding and intron loss.
Collapse
Affiliation(s)
- Xian-Chun Zeng
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan 430074, People's Republic of China.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
A new study reports creation of spliceosomal introns in multiple related fungal species by proliferation of cryptic elements. Resonances to a case in unrelated algae suggest such elements hold general answers to long-standing mysteries of intron evolution.
Collapse
Affiliation(s)
- Scott William Roy
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
| | | |
Collapse
|
33
|
Hill N, Leow A, Bleidorn C, Groth D, Tiedemann R, Selbig J, Hartmann S. Analysis of phylogenetic signal in protostomial intron patterns using Mutual Information. Theory Biosci 2012; 132:93-104. [DOI: 10.1007/s12064-012-0173-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 11/30/2012] [Indexed: 11/29/2022]
|
34
|
Yenerall P, Zhou L. Identifying the mechanisms of intron gain: progress and trends. Biol Direct 2012; 7:29. [PMID: 22963364 PMCID: PMC3443670 DOI: 10.1186/1745-6150-7-29] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/22/2012] [Indexed: 12/22/2022] Open
Abstract
Abstract Continued improvements in Next-Generation DNA/RNA sequencing coupled with advances in gene annotation have provided researchers access to a plethora of annotated genomes. Subsequent analyses of orthologous gene structures have identified numerous intron gain and loss events that have occurred both recently and in the very distant past. This research has afforded exceptional insight into the temporal and lineage-specific rates of intron gain and loss among various species throughout evolution. Numerous studies have also attempted to identify the molecular mechanisms of intron gain and loss. However, even after considerable effort, very little is known about these processes. In particular, the mechanism(s) of intron gain have proven exceptionally enigmatic and remain topics of considerable debate. Currently, there exists no definitive consensus as to what mechanism(s) may generate introns. Because many introns are known to affect gene expression, it is necessary to understand the molecular process(es) by which introns may be gained. Here we review the seven most commonly purported mechanisms of intron gain and, when possible, summarize molecular evidence for or against the occurrence of each of these mechanisms. Furthermore, we catalogue indirect evidence that supports the occurrence of each mechanism. Finally, because these proposed mechanisms fail to explain the mechanistic origin of many recently gained introns, we also look at trends that may aid researchers in identifying other potential mechanism(s) of intron gain. Reviewers This article was reviewed by Eugene Koonin, Scott Roy (nominated by W. Ford Doolittle), and John Logsdon.
Collapse
Affiliation(s)
- Paul Yenerall
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | |
Collapse
|
35
|
van der Burgt A, Severing E, de Wit PJGM, Collemare J. Birth of new spliceosomal introns in fungi by multiplication of introner-like elements. Curr Biol 2012; 22:1260-5. [PMID: 22658596 DOI: 10.1016/j.cub.2012.05.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/12/2012] [Accepted: 05/03/2012] [Indexed: 11/25/2022]
Abstract
Spliceosomal introns are noncoding sequences that separate exons in eukaryotic genes and are removed from pre-messenger RNAs by the splicing machinery. Their origin has remained a mystery in biology since their discovery because intron gains seem to be infrequent in many eukaryotic lineages. Although a few recent intron gains have been reported, none of the proposed gain mechanisms can convincingly explain the high number of introns in present-day eukaryotic genomes. Here we report on particular spliceosomal introns that share high sequence similarity and are reminiscent of introner elements. These elements multiplied in unrelated genes of six fungal genomes and account for the vast majority of intron gains in these fungal species. Such introner-like elements (ILEs) contain all typical characteristics of regular spliceosomal introns (RSIs) but are longer and predicted to harbor more stable secondary structures. However, dating of multiplication events showed that they degenerate in sequence and length within 100,000 years to eventually become indistinguishable from RSIs. We suggest that ILEs not only account for intron gains in six fungi but also in ancestral eukaryotes to give rise to most RSIs by a yet unknown multiplication mechanism.
Collapse
Affiliation(s)
- Ate van der Burgt
- Laboratory of Phytopathology, Wageningen University, 6708PB Wageningen, The Netherlands.
| | | | | | | |
Collapse
|
36
|
What Can Domesticated Genes Tell Us about the Intron Gain in Mammals? INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:278981. [PMID: 22693680 PMCID: PMC3369469 DOI: 10.1155/2012/278981] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 04/06/2012] [Indexed: 01/21/2023]
Abstract
Domesticated genes, originating from retroelements or from DNA-transposons, constitute an ideal system for testing the hypothesis on the absence of intron gain in mammals. Since single-copy domesticated genes originated from the intronless multicopy transposable elements, the ancestral intron state for domesticated genes is zero. A phylogenomic approach has been used to analyse all domesticated genes in mammals and chordates that originated from the coding parts of transposable elements. A significant amount of intron gain was found only in domesticated genes of placental mammals, where more than 70 cases were identified. De novo gained introns show clear positional bias, since they are distributed mainly in 5′ UTR and coding regions, while 3′ UTR introns are very rare. In the coding regions of some domesticated genes up to 8 de novo gained introns have been found. Surprisingly, the majority of intron gains have occurred in the ancestor of placental mammals. Domesticated genes could constitute an excellent system on which to analyse the mechanisms of intron gain. This paper summarizes the current understanding of intron gain in mammals.
Collapse
|
37
|
Rogozin IB, Carmel L, Csuros M, Koonin EV. Origin and evolution of spliceosomal introns. Biol Direct 2012; 7:11. [PMID: 22507701 PMCID: PMC3488318 DOI: 10.1186/1745-6150-7-11] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 03/15/2012] [Indexed: 12/31/2022] Open
Abstract
Evolution of exon-intron structure of eukaryotic genes has been a matter of long-standing, intensive debate. The introns-early concept, later rebranded ‘introns first’ held that protein-coding genes were interrupted by numerous introns even at the earliest stages of life's evolution and that introns played a major role in the origin of proteins by facilitating recombination of sequences coding for small protein/peptide modules. The introns-late concept held that introns emerged only in eukaryotes and new introns have been accumulating continuously throughout eukaryotic evolution. Analysis of orthologous genes from completely sequenced eukaryotic genomes revealed numerous shared intron positions in orthologous genes from animals and plants and even between animals, plants and protists, suggesting that many ancestral introns have persisted since the last eukaryotic common ancestor (LECA). Reconstructions of intron gain and loss using the growing collection of genomes of diverse eukaryotes and increasingly advanced probabilistic models convincingly show that the LECA and the ancestors of each eukaryotic supergroup had intron-rich genes, with intron densities comparable to those in the most intron-rich modern genomes such as those of vertebrates. The subsequent evolution in most lineages of eukaryotes involved primarily loss of introns, with only a few episodes of substantial intron gain that might have accompanied major evolutionary innovations such as the origin of metazoa. The original invasion of self-splicing Group II introns, presumably originating from the mitochondrial endosymbiont, into the genome of the emerging eukaryote might have been a key factor of eukaryogenesis that in particular triggered the origin of endomembranes and the nucleus. Conversely, splicing errors gave rise to alternative splicing, a major contribution to the biological complexity of multicellular eukaryotes. There is no indication that any prokaryote has ever possessed a spliceosome or introns in protein-coding genes, other than relatively rare mobile self-splicing introns. Thus, the introns-first scenario is not supported by any evidence but exon-intron structure of protein-coding genes appears to have evolved concomitantly with the eukaryotic cell, and introns were a major factor of evolution throughout the history of eukaryotes. This article was reviewed by I. King Jordan, Manuel Irimia (nominated by Anthony Poole), Tobias Mourier (nominated by Anthony Poole), and Fyodor Kondrashov. For the complete reports, see the Reviewers’ Reports section.
Collapse
Affiliation(s)
- Igor B Rogozin
- National Center for Biotechnology Information NLM/NIH, 8600 Rockville Pike, Bldg, 38A, Bethesda, MD 20894, USA
| | | | | | | |
Collapse
|
38
|
Abstract
The recent explosion of genome sequences from all major phylogenetic groups has unveiled an unexpected wealth of cases of recurrent evolution of strikingly similar genomic features in different lineages. Here, we review the diverse known types of recurrent evolution in eukaryotic genomes, with a special focus on metazoans, ranging from reductive genome evolution to origins of splice-leader trans-splicing, from tandem exon duplications to gene family expansions. We first propose a general classification scheme for evolutionary recurrence at the genomic level, based on the type of driving force-mutation or selection-and the environmental and genomic circumstances underlying these forces. We then discuss various cases of recurrent genomic evolution under this scheme. Finally, we provide a broader context for repeated genomic evolution, including the unique relationship of genomic recurrence with the genotype-phenotype map, and the ways in which the study of recurrent genomic evolution can be used to understand fundamental evolutionary processes.
Collapse
Affiliation(s)
- Ignacio Maeso
- Department of Zoology, University of Oxford, United Kingdom
| | - Scott William Roy
- Department of Biology, Stanford University
- Department of Biology, San Francisco State University
| | - Manuel Irimia
- Department of Biology, Stanford University
- Banting and Best Department of Medical Research, Donnelly Centre, University of Toronto, Canada
| |
Collapse
|
39
|
Croll D, McDonald BA. Intron gains and losses in the evolution of Fusarium and Cryptococcus fungi. Genome Biol Evol 2012; 4:1148-61. [PMID: 23054310 PMCID: PMC3514964 DOI: 10.1093/gbe/evs091] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2012] [Indexed: 12/15/2022] Open
Abstract
The presence of spliceosomal introns in eukaryotic genes poses a major puzzle for the study of genome evolution. Intron densities vary enormously among distant lineages. However, the mechanisms driving intron gains are poorly understood and very few intron gains and losses have been documented over short evolutionary time spans. Fungi emerged recently as excellent models to study intron evolution and "reverse splicing" was found to be a major driver of recent intron gains in a clade of ascomycete fungi. We screened a total of 38 genomes from two fungal clades important in medicine and agriculture to identify intron gains and losses both within and between species. We detected 86 and 198 variable intron positions in the Cryptococcus and Fusarium clades, respectively. Some genes underwent extensive changes in their exon-intron structure, with up to six variable intron positions per gene. We identified a very recently gained intron in a group of tomato-infecting strains belonging to the F. oxysporum species complex. In the human pathogen C. gattii, we found recent intron losses in subtypes of the species. The two studied fungal clades provided evidence for extensive changes in their exon-intron structure within and among closely related species. We show that both intronization of previously coding DNA and insertion of exogenous DNA are the major drivers of intron gains.
Collapse
Affiliation(s)
- Daniel Croll
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Switzerland.
| | | |
Collapse
|
40
|
Guida A, Lindstädt C, Maguire SL, Ding C, Higgins DG, Corton NJ, Berriman M, Butler G. Using RNA-seq to determine the transcriptional landscape and the hypoxic response of the pathogenic yeast Candida parapsilosis. BMC Genomics 2011; 12:628. [PMID: 22192698 PMCID: PMC3287387 DOI: 10.1186/1471-2164-12-628] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 12/22/2011] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Candida parapsilosis is one of the most common causes of Candida infection worldwide. However, the genome sequence annotation was made without experimental validation and little is known about the transcriptional landscape. The transcriptional response of C. parapsilosis to hypoxic (low oxygen) conditions, such as those encountered in the host, is also relatively unexplored. RESULTS We used next generation sequencing (RNA-seq) to determine the transcriptional profile of C. parapsilosis growing in several conditions including different media, temperatures and oxygen concentrations. We identified 395 novel protein-coding sequences that had not previously been annotated. We removed > 300 unsupported gene models, and corrected approximately 900. We mapped the 5' and 3' UTR for thousands of genes. We also identified 422 introns, including two introns in the 3' UTR of one gene. This is the first report of 3' UTR introns in the Saccharomycotina. Comparing the introns in coding sequences with other species shows that small numbers have been gained and lost throughout evolution. Our analysis also identified a number of novel transcriptional active regions (nTARs). We used both RNA-seq and microarray analysis to determine the transcriptional profile of cells grown in normoxic and hypoxic conditions in rich media, and we showed that there was a high correlation between the approaches. We also generated a knockout of the UPC2 transcriptional regulator, and we found that similar to C. albicans, Upc2 is required for conferring resistance to azole drugs, and for regulation of expression of the ergosterol pathway in hypoxia. CONCLUSION We provide the first detailed annotation of the C. parapsilosis genome, based on gene predictions and transcriptional analysis. We identified a number of novel ORFs and other transcribed regions, and detected transcripts from approximately 90% of the annotated protein coding genes. We found that the transcription factor Upc2 role has a conserved role as a major regulator of the hypoxic response in C. parapsilosis and C. albicans.
Collapse
Affiliation(s)
- Alessandro Guida
- School of Medicine and Medical Science, Conway Institute, UniversityCollege Dublin, Belfield, Dublin 4, Ireland
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Extensive intron gain in the ancestor of placental mammals. Biol Direct 2011; 6:59. [PMID: 22112745 PMCID: PMC3257199 DOI: 10.1186/1745-6150-6-59] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/23/2011] [Indexed: 01/29/2023] Open
Abstract
Background Genome-wide studies of intron dynamics in mammalian orthologous genes have found convincing evidence for loss of introns but very little for intron turnover. Similarly, large-scale analysis of intron dynamics in a few vertebrate genomes has identified only intron losses and no gains, indicating that intron gain is an extremely rare event in vertebrate evolution. These studies suggest that the intron-rich genomes of vertebrates do not allow intron gain. The aim of this study was to search for evidence of de novo intron gain in domesticated genes from an analysis of their exon/intron structures. Results A phylogenomic approach has been used to analyse all domesticated genes in mammals and chordates that originated from the coding parts of transposable elements. Gain of introns in domesticated genes has been reconstructed on well established mammalian, vertebrate and chordate phylogenies, and examined as to where and when the gain events occurred. The locations, sizes and amounts of de novo introns gained in the domesticated genes during the evolution of mammals and chordates has been analyzed. A significant amount of intron gain was found only in domesticated genes of placental mammals, where more than 70 cases were identified. De novo gained introns show clear positional bias, since they are distributed mainly in 5' UTR and coding regions, while 3' UTR introns are very rare. In the coding regions of some domesticated genes up to 8 de novo gained introns have been found. Intron densities in Eutheria-specific domesticated genes and in older domesticated genes that originated early in vertebrates are lower than those for normal mammalian and vertebrate genes. Surprisingly, the majority of intron gains have occurred in the ancestor of placentals. Conclusions This study provides the first evidence for numerous intron gains in the ancestor of placental mammals and demonstrates that adequate taxon sampling is crucial for reconstructing intron evolution. The findings of this comprehensive study slightly challenge the current view on the evolutionary stasis in intron dynamics during the last 100 - 200 My. Domesticated genes could constitute an excellent system on which to analyse the mechanisms of intron gain in placental mammals. Reviewers: this article was reviewed by Dan Graur, Eugene V. Koonin and Jürgen Brosius.
Collapse
|
42
|
Torriani SFF, Stukenbrock EH, Brunner PC, McDonald BA, Croll D. Evidence for extensive recent intron transposition in closely related fungi. Curr Biol 2011; 21:2017-22. [PMID: 22100062 DOI: 10.1016/j.cub.2011.10.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 10/26/2011] [Accepted: 10/26/2011] [Indexed: 11/30/2022]
Abstract
Though spliceosomal introns are a major structural component of most eukaryotic genes and intron density varies by more than three orders of magnitude among eukaryotes [1-3], the origins of introns are poorly understood, and only a few cases of unambiguous intron gain are known [4-8]. We utilized population genomic comparisons of three closely related fungi to identify crucial transitory phases of intron gain and loss. We found 74 intron positions showing intraspecific presence-absence polymorphisms (PAPs) for the entire intron. Population genetic analyses identified intron PAPs at different stages of fixation and showed that intron gain or loss was very recent. We found direct support for extensive intron transposition among unrelated genes. A substantial proportion of highly similar introns in the genome either were recently gained or showed a transient phase of intron PAP. We also identified an intron transfer among paralogous genes that created a new intron. Intron loss was due mainly to homologous recombination involving reverse-transcribed mRNA. The large number of intron positions in transient phases of either intron gain or loss shows that intron evolution is much faster than previously thought and provides an excellent model to study molecular mechanisms of intron gain.
Collapse
Affiliation(s)
- Stefano F F Torriani
- Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH Zurich), 8092 Zurich, Switzerland
| | | | | | | | | |
Collapse
|
43
|
Cohen NE, Shen R, Carmel L. The role of reverse transcriptase in intron gain and loss mechanisms. Mol Biol Evol 2011; 29:179-86. [PMID: 21804076 DOI: 10.1093/molbev/msr192] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Intron density is highly variable across eukaryotic species. It seems that different lineages have experienced considerably different levels of intron gain and loss events, but the reasons for this are not well known. A large number of mechanisms for intron loss and gain have been suggested, and most of them have at least some level of indirect support. We therefore figured out that the variability in intron density can be a reflection of the fact that different mechanisms are active in different lineages. Quite a number of these putative mechanisms, both for intron loss and for intron gain, postulate that the enzyme reverse transcriptase (RT) has a key role in the process. In this paper, we lay out three predictions whose approval or falsification gives indication for the involvement of RT in intron gain and loss processes. Testing these predictions requires data on the intron gain and loss rates of individual genes along different branches of the eukaryotic phylogenetic tree. So far, such rates could not be computed, and hence, these predictions could not be rigorously evaluated. Here, we use a maximum likelihood algorithm that we have devised in the past, Evolutionary Reconstruction by Expectation Maximization, which allows the estimation of such rates. Using this algorithm, we computed the intron loss and gain rates of more than 300 genes in each branch of the phylogenetic tree of 19 eukaryotic species. Based on that we found only little support for RT activity in intron gain. In contrast, we suggest that RT-mediated intron loss is a mechanism that is very efficient in removing introns, and thus, its levels of activity may be a major determinant of intron number. Moreover, we found that intron gain and loss rates are negatively correlated in intron-poor species but are positively correlated for intron-rich species. One explanation to this is that intron gain and loss mechanisms in intron-rich species (like metazoans) share a common mechanistic component, albeit not a RT.
Collapse
Affiliation(s)
- Noa E Cohen
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | | |
Collapse
|
44
|
Miskei M, Ádám C, Kovács L, Karányi Z, Dombrádi V. Molecular evolution of phosphoprotein phosphatases in Drosophila. PLoS One 2011; 6:e22218. [PMID: 21789237 PMCID: PMC3137614 DOI: 10.1371/journal.pone.0022218] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 06/20/2011] [Indexed: 12/25/2022] Open
Abstract
Phosphoprotein phosphatases (PPP), these ancient and important regulatory enzymes are present in all eukaryotic organisms. Based on the genome sequences of 12 Drosophila species we traced the evolution of the PPP catalytic subunits and noted a substantial expansion of the gene family. We concluded that the 18–22 PPP genes of Drosophilidae were generated from a core set of 8 indispensable phosphatases that are present in most of the insects. Retropositons followed by tandem gene duplications extended the phosphatase repertoire, and sporadic gene losses contributed to the species specific variations in the PPP complement. During the course of these studies we identified 5, up till now uncharacterized phosphatase retrogenes: PpY+, PpD5+, PpD6+, Pp4+, and Pp6+ which are found only in some ancient Drosophila. We demonstrated that all of these new PPP genes exhibit a distinct male specific expression. In addition to the changes in gene numbers, the intron-exon structure and the chromosomal localization of several PPP genes was also altered during evolution. The G−C content of the coding regions decreased when a gene moved into the heterochromatic region of chromosome Y. Thus the PPP enzymes exemplify the various types of dynamic rearrangements that accompany the molecular evolution of a gene family in Drosophilidae.
Collapse
Affiliation(s)
- Márton Miskei
- Centre for Agricultural and Applied Economic Sciences, Institute of Horticultural Sciences, Department of Plant Biotechnology, University of Debrecen, Debrecen, Hungary
| | - Csaba Ádám
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - László Kovács
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Zsolt Karányi
- First Department of Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Viktor Dombrádi
- Department of Medical Chemistry, Research Center for Molecular Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
- * E-mail:
| |
Collapse
|
45
|
Irimia M, Maeso I, Burguera D, Hidalgo-Sánchez M, Puelles L, Roy SW, Garcia-Fernàndez J, Ferran JL. Contrasting 5' and 3' evolutionary histories and frequent evolutionary convergence in Meis/hth gene structures. Genome Biol Evol 2011; 3:551-64. [PMID: 21680890 PMCID: PMC3140891 DOI: 10.1093/gbe/evr056] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Organisms show striking differences in genome structure; however, the functional implications and fundamental forces that govern these differences remain obscure. The intron–exon organization of nuclear genes is involved in a particularly large variety of structures and functional roles. We performed a 22-species study of Meis/hth genes, intron-rich homeodomain-containing transcription factors involved in a wide range of developmental processes. Our study revealed three surprising results that suggest important and very different functions for Meis intron–exon structures. First, we find unexpected conservation across species of intron positions and lengths along most of the Meis locus. This contrasts with the high degree of structural divergence found in genome-wide studies and may attest to conserved regulatory elements residing within these conserved introns. Second, we find very different evolutionary histories for the 5′ and 3′ regions of the gene. The 5′-most 10 exons, which encode the highly conserved Meis domain and homeodomain, show striking conservation. By contrast, the 3′ of the gene, which encodes several domains implicated in transcriptional activation and response to cell signaling, shows a remarkably active evolutionary history, with diverse isoforms and frequent creation and loss of new exons and splice sites. This region-specific diversity suggests evolutionary “tinkering,” with alternative splicing allowing for more subtle regulation of protein function. Third, we find a large number of cases of convergent evolution in the 3′ region, including 1) parallel losses of ancestral coding sequence, 2) parallel gains of external and internal splice sites, and 3) recurrent truncation of C-terminal coding regions. These results attest to the importance of locus-specific splicing functions in differences in structural evolution across genes, as well as to commonalities of forces shaping the evolution of individual genes along different lineages.
Collapse
Affiliation(s)
- Manuel Irimia
- Department of Genetics, School of Biology, University of Barcelona, Barcelona, Spain.
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Wang D, Yu J. Both size and GC-content of minimal introns are selected in human populations. PLoS One 2011; 6:e17945. [PMID: 21437290 PMCID: PMC3060096 DOI: 10.1371/journal.pone.0017945] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 02/16/2011] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND We previously have studied the insertion and deletion polymorphism by sequencing no more than one hundred introns in a mixed human population and found that the minimal introns tended to maintain length at an optimal size. Here we analyzed re-sequenced 179 individual genomes (from African, European, and Asian populations) from the data released by the 1000 Genome Project to study the size dynamics of minimal introns. PRINCIPAL FINDINGS We not only confirmed that minimal introns in human populations are selected but also found two major effects in minimal intron evolution: (i) Size-effect: minimal introns longer than an optimal size (87 nt) tend to have a higher ratio of deletion to insertion than those that are shorter than the optimal size; (ii) GC-effect: minimal introns with lower GC content tend to be more frequently deleted than those with higher GC content. The GC-effect results in a higher GC content in minimal introns than their flanking exons as opposed to larger introns (≥125 nt) that always have a lower GC content than that of their flanking exons. We also observed that the two effects are distinguishable but not completely separable within and between populations. CONCLUSIONS We validated the unique mutation dynamics of minimal introns in keeping their near-optimal size and GC content, and our observations suggest potentially important functions of human minimal introns in transcript processing and gene regulation.
Collapse
Affiliation(s)
- Dapeng Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
- Graduate University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Jun Yu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China
| |
Collapse
|
47
|
|
48
|
Goh MY, Pan MZ, Blake DP, Wan KL, Song BK. Eimeria maxima phosphatidylinositol 4-phosphate 5-kinase: locus sequencing, characterization, and cross-phylum comparison. Parasitol Res 2011; 108:611-20. [PMID: 20938684 DOI: 10.1007/s00436-010-2104-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Accepted: 09/23/2010] [Indexed: 10/19/2022]
Abstract
Phosphatidylinositol 4-phosphate 5-kinase (PIP5K) may play an important role in host-cell invasion by the Eimeria species, protozoan parasites which can cause severe intestinal disease in livestock. Here, we report the structural organization of the PIP5K gene in Eimeria maxima (Weybridge strain). Two E. maxima BAC clones carrying the E. maxima PIP5K (EmPIP5K) coding sequences were selected for shotgun sequencing, yielding a 9.1-kb genomic segment. The EmPIP5K coding region was initially identified using in silico gene-prediction approaches and subsequently confirmed by mapping rapid amplification of cDNA ends and RT-PCR-generated cDNA sequence to its genomic segment. The putative EmPIP5K gene was located at position 710-8036 nt on the complimentary strand and comprised of 23 exons. Alignment of the 1147 amino acid sequence with previously annotated PIP5K proteins from other Apicomplexa species detected three conserved motifs encompassing the kinase core domain, which has been shown by previous protein deletion studies to be necessary for PIP5K protein function. Phylogenetic analysis provided further evidence that the putative EmPIP5K protein is orthologous to that of other Apicomplexa. Subsequent comparative gene structure characterization revealed events of intron loss/gain throughout the evolution of the apicomplexan PIP5K gene. Further scrutiny of the genomic structure revealed a possible trend towards "intron gain" between two of the motif regions. Our findings offer preliminary insights into the structural variations that have occurred during the evolution of the PIP5K locus and may aid in understanding the functional role of this gene in the cellular biology of apicomplexan parasites.
Collapse
Affiliation(s)
- Mei-Yen Goh
- School of Science, Monash University Sunway Campus, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor, DE, Malaysia
| | | | | | | | | |
Collapse
|
49
|
Yang Z, Huang J. De novo origin of new genes with introns in Plasmodium vivax. FEBS Lett 2011; 585:641-4. [PMID: 21241695 DOI: 10.1016/j.febslet.2011.01.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 01/08/2011] [Accepted: 01/11/2011] [Indexed: 11/26/2022]
Abstract
The origin of new genes is critical for organisms adapting to new niches. Here, we present evidence for a recent de novo origin of at least 13 protein-coding genes in the genome of Plasmodium vivax. Although recently de novo originated genes have often been suggested to be initially intronless, five of the genes identified in our analysis contain introns in their coding regions. Further investigations revealed that these introns likely evolved from previously intergenic regions together with the coding sequences. We discuss the potential mechanisms for intron formation in these genes and propose that intronization be considered in the formation of de novo originated genes.
Collapse
Affiliation(s)
- Zefeng Yang
- Department of Biology, East Carolina University, Greenville, NC 27858, USA
| | | |
Collapse
|
50
|
Ragg H. Intron creation and DNA repair. Cell Mol Life Sci 2011; 68:235-42. [PMID: 20853128 PMCID: PMC11115024 DOI: 10.1007/s00018-010-0532-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 09/07/2010] [Accepted: 09/07/2010] [Indexed: 10/19/2022]
Abstract
The genesis of the exon-intron patterns of eukaryotic genes persists as one of the most enigmatic questions in molecular genetics. In particular, the origin and mechanisms responsible for creation of spliceosomal introns have remained controversial. Now the issue appears to have taken a turn. The formation of novel introns in eukaryotes, including some vertebrate lineages, is not as rare as commonly assumed. Moreover, introns appear to have been gained in parallel at closely spaced sites and even repeatedly at the same position. Based on these discoveries, novel hypotheses of intron creation have been developed. The new concepts posit that DNA repair processes are a major source of intron formation. Here, after summarizing the current views of intron gain mechanisms, I review findings in support of the DNA repair hypothesis that provides a global mechanistic scenario for intron creation. Some implications on our perception of the mosaic structure of eukaryotic genes are also discussed.
Collapse
Affiliation(s)
- Hermann Ragg
- Department of Biotechnology, University of Bielefeld, Germany.
| |
Collapse
|