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Hatanaka R, Tamagawa K, Haruta N, Sugimoto A. The impact of differential transposition activities of autonomous and nonautonomous hAT transposable elements on genome architecture and gene expression in Caenorhabditis inopinata. Genetics 2024; 227:iyae052. [PMID: 38577765 DOI: 10.1093/genetics/iyae052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 01/08/2024] [Accepted: 03/28/2024] [Indexed: 04/06/2024] Open
Abstract
Transposable elements are DNA sequences capable of moving within genomes and significantly influence genomic evolution. The nematode Caenorhabditis inopinata exhibits a much higher transposable element copy number than its sister species, Caenorhabditis elegans. In this study, we identified a novel autonomous transposable element belonging to the hAT superfamily from a spontaneous transposable element-insertion mutant in C. inopinata and named this transposon Ci-hAT1. Further bioinformatic analyses uncovered 3 additional autonomous hAT elements-Ci-hAT2, Ci-hAT3, and Ci-hAT4-along with over 1,000 copies of 2 nonautonomous miniature inverted-repeat transposable elements, mCi-hAT1 and mCi-hAT4, likely derived from Ci-hAT1 and Ci-hAT4 through internal deletion. We tracked at least 3 sequential transpositions of Ci-hAT1 over several years. However, the transposition rates of the other 3 autonomous hAT elements were lower, suggesting varying activity levels. Notably, the distribution patterns of the 2 miniature inverted-repeat transposable element families differed significantly: mCi-hAT1 was primarily located in the chromosome arms, a pattern observed in the transposable elements of other Caenorhabditis species, whereas mCi-hAT4 was more evenly distributed across chromosomes. Additionally, interspecific transcriptome analysis indicated that C. inopinata genes with upstream or intronic these miniature inverted-repeat transposable element insertions tend to be more highly expressed than their orthologous genes in C. elegans. These findings highlight the significant role of de-silenced transposable elements in driving the evolution of genomes and transcriptomes, leading to species-specific genetic diversity.
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Affiliation(s)
- Ryuhei Hatanaka
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Katsunori Tamagawa
- Laboratory of Evolutionary Genomics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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Sarilar V, Bleykasten-Grosshans C, Neuvéglise C. Evolutionary dynamics of hAT DNA transposon families in Saccharomycetaceae. Genome Biol Evol 2014; 7:172-90. [PMID: 25532815 PMCID: PMC4316626 DOI: 10.1093/gbe/evu273] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Transposable elements (TEs) are widespread in eukaryotes but uncommon in yeasts of the Saccharomycotina subphylum, in terms of both host species and genome fraction. The class II elements are especially scarce, but the hAT element Rover is a noteworthy exception that deserves further investigation. Here, we conducted a genome-wide analysis of hAT elements in 40 ascomycota. A novel family, Roamer, was found in three species, whereas Rover was detected in 15 preduplicated species from Kluyveromyces, Eremothecium, and Lachancea genera, with up to 41 copies per genome. Rover acquisition seems to have occurred by horizontal transfer in a common ancestor of these genera. The detection of remote Rover copies in Naumovozyma dairenensis and in the sole Saccharomyces cerevisiae strain AWRI1631, without synteny, suggests that two additional independent horizontal transfers took place toward these genomes. Such patchy distribution of elements prevents any anticipation of TE presence in incoming sequenced genomes, even closely related ones. The presence of both putative autonomous and defective Rover copies, as well as their diversification into five families, indicate particular dynamics of Rover elements in the Lachancea genus. Especially, we discovered the first miniature inverted-repeat transposable elements (MITEs) to be described in yeasts, together with their parental autonomous copies. Evidence of MITE insertion polymorphism among Lachancea waltii strains suggests their recent activity. Moreover, 40% of Rover copies appeared to be involved in chromosome rearrangements, showing the large structural impact of TEs on yeast genome and opening the door to further investigations to understand their functional and evolutionary consequences.
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Affiliation(s)
- Véronique Sarilar
- INRA, UMR 1319 Micalis, Jouy-en-Josas, France AgroParisTech, UMR Micalis, Jouy-en-Josas, France
| | - Claudine Bleykasten-Grosshans
- CNRS, UMR 7156, Laboratoire de Génétique Moléculaire, Génomique et Microbiologie, Université de Strasbourg, Strasbourg, France
| | - Cécile Neuvéglise
- INRA, UMR 1319 Micalis, Jouy-en-Josas, France AgroParisTech, UMR Micalis, Jouy-en-Josas, France
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Ladevèze V, Chaminade N, Lemeunier F, Periquet G, Aulard S. General survey of hAT transposon superfamily with highlight on hobo element in Drosophila. Genetica 2012; 140:375-92. [DOI: 10.1007/s10709-012-9687-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/10/2012] [Indexed: 11/30/2022]
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Hickman AB, Chandler M, Dyda F. Integrating prokaryotes and eukaryotes: DNA transposases in light of structure. Crit Rev Biochem Mol Biol 2010; 45:50-69. [PMID: 20067338 DOI: 10.3109/10409230903505596] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
DNA rearrangements are important in genome function and evolution. Genetic material can be rearranged inadvertently during processes such as DNA repair, or can be moved in a controlled manner by enzymes specifically dedicated to the task. DNA transposases comprise one class of such enzymes. These move DNA segments known as transposons to new locations, without the need for sequence homology between transposon and target site. Several biochemically distinct pathways have evolved for DNA transposition, and genetic and biochemical studies have provided valuable insights into many of these. However, structural information on transposases - particularly with DNA substrates - has proven elusive in most cases. On the other hand, large-scale genome sequencing projects have led to an explosion in the number of annotated prokaryotic and eukaryotic mobile elements. Here, we briefly review biochemical and mechanistic aspects of DNA transposition, and propose that integrating sequence information with structural information using bioinformatics tools such as secondary structure prediction and protein threading can lead not only to an additional level of understanding but possibly also to testable hypotheses regarding transposition mechanisms. Detailed understanding of transposition pathways is a prerequisite for the long-term goal of exploiting DNA transposons as genetic tools and as a basis for genetic medical applications.
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Affiliation(s)
- Alison Burgess Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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Keith JH, Schaeper CA, Fraser TS, Fraser MJ. Mutational analysis of highly conserved aspartate residues essential to the catalytic core of the piggyBac transposase. BMC Mol Biol 2008; 9:73. [PMID: 18694512 PMCID: PMC2533014 DOI: 10.1186/1471-2199-9-73] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 08/11/2008] [Indexed: 01/08/2023] Open
Abstract
Background The piggyBac mobile element is quickly gaining popularity as a tool for the transgenesis of many eukaryotic organisms. By studying the transposase which catalyzes the movement of piggyBac, we may be able to modify this vector system to make it a more effective transgenesis tool. In a previous publication, Sarkar A, Sim C, Hong YS, Hogan JR, Fraser MJ, Robertson HM, and Collins FH have proposed the presence of the widespread 'DDE/DDD' motif for piggyBac at amino acid positions D268, D346, and D447. Results This study utilizes directed mutagenesis and plasmid-based mobility assays to assess the importance of these residues as the catalytic core of the piggyBac transposase. We have functionally analyzed individual point-mutations with respect to charge and physical size in all three proposed residues of the 'DDD' motif as well as another nearby, highly conserved aspartate at D450. All of our mutations had a significant effect on excision frequency in S2 cell cultures. We have also aligned the piggyBac transposase to other close family members, both functional and non-functional, in an attempt to identify the most highly conserved regions and position a number of interesting features. Conclusion We found all the designated DDD aspartates reside in clusters of amino acids that conserved among piggyBac family transposase members. Our results indicate that all four aspartates are necessary, to one degree or another, for excision to occur in a cellular environment, but D450 seems to have a tolerance for a glutamate substitution. All mutants tested significantly decreased excision frequency in cell cultures when compared with the wild-type transposase.
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Zhou F, Olman V, Xu Y. Insertion Sequences show diverse recent activities in Cyanobacteria and Archaea. BMC Genomics 2008; 9:36. [PMID: 18218090 PMCID: PMC2246112 DOI: 10.1186/1471-2164-9-36] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Accepted: 01/24/2008] [Indexed: 11/11/2022] Open
Abstract
Background Mobile genetic elements (MGEs) play an essential role in genome rearrangement and evolution, and are widely used as an important genetic tool. Results In this article, we present genetic maps of recently active Insertion Sequence (IS) elements, the simplest form of MGEs, for all sequenced cyanobacteria and archaea, predicted based on the previously identified ~1,500 IS elements. Our predicted IS maps are consistent with the NCBI annotations of the IS elements. By linking the predicted IS elements to various characteristics of the organisms under study and the organism's living conditions, we found that (a) the activities of IS elements heavily depend on the environments where the host organisms live; (b) the number of recently active IS elements in a genome tends to increase with the genome size; (c) the flanking regions of the recently active IS elements are significantly enriched with genes encoding DNA binding factors, transporters and enzymes; and (d) IS movements show no tendency to disrupt operonic structures. Conclusion This is the first genome-scale maps of IS elements with detailed structural information on the sequence level. These genetic maps of recently active IS elements and the several interesting observations would help to improve our understanding of how IS elements proliferate and how they are involved in the evolution of the host genomes.
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Affiliation(s)
- Fengfeng Zhou
- Computational Systems Biology Laboratory, Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA.
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Kikuno K, Tanaka K, Itoh M, Tanaka Y, Boussy IA, Gamo S. Patterns of hobo elements and their effects in natural populations of Drosophila melanogaster in Japan. Heredity (Edinb) 2006; 96:426-33. [PMID: 16639422 DOI: 10.1038/sj.hdy.6800816] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We studied the dynamics of hobo elements of Drosophila melanogaster in Japan with the goal of better understanding the invasion and evolution of transposons in natural populations. One hundred and twenty-six isofemale lines and 11 older stocks were tested for the presence and genetic phenotype of hobo elements. The oldest H strain, containing complete and deleted hobo elements, is Hikone-H (1957), but Hikone-R (1952) has no hobo-homologous sequences. The findings suggest that the hobo element invaded Japanese populations in the mid-1950s, at about the same time as the P element invasion in Japan. This chronology is consistent with the hypothesis of a recent worldwide hobo element invasion into D. melanogaster in the mid-1950s. In recently collected populations, H degrees strains (low hobo activity and high repression potency) are predominant, whereas H+ strains (high hobo activity and high repression potency) are predominant in the Sakishima Islands, the most southwestern islands of the Japanese archipelago. H' strains (high hobo activity and low repression potency) were first found in limited island populations. Japanese populations have not only full-size hobo elements and 1.5 kb Th elements but also characteristic deletion derivatives (1.6 and 1.8 kb XhoI fragments) that we have named Jh elements. These results are consistent with transgenic experiments with complete hobo elements, in which populations evolved to H+ or H degrees via H', and in which 1.8 kb fragments appeared. We conclude that hobo elements invaded the central region of Japan, spread to the far islands, and that the invasion is currently at an intermediate, nonequilibrium stage.
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Affiliation(s)
- K Kikuno
- Department of Earth and Life Sciences, Osaka Prefecture University, 1-1 Gakuen-Cho, Sakai 599-8531, Japan
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Chesney MA, Kidd AR, Kimble J. gon-14 functions with class B and class C synthetic multivulva genes to control larval growth in Caenorhabditis elegans. Genetics 2006; 172:915-28. [PMID: 16322520 PMCID: PMC1383727 DOI: 10.1534/genetics.105.048751] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 11/09/2005] [Indexed: 12/11/2022] Open
Abstract
Previous work showed that C. elegans gon-14 is required for gonadogenesis. Here we report that gon-14 encodes a protein with similarity to LIN-15B, a class B synMuv protein. An extensive region of GON-14 contains blocks of sequence similarity to transposases of the hAT superfamily, but key residues are not conserved, suggesting a distant relationship. GON-14 also contains a putative THAP DNA-binding domain. A rescuing gon-14::GON-14::VENUS reporter is broadly expressed during development and localizes to the nucleus. Strong loss-of-function and predicted null gon-14 alleles have pleiotropic defects, including multivulval (Muv) defects and temperature-sensitive larval arrest. Although the gon-14 Muv defect is not enhanced by synMuv mutations, gon-14 interacts genetically with class B and class C synMuv genes, including lin-35/Rb, let-418/Mi-2beta, and trr-1/TRRAP. The gon-14; synMuv double mutants arrest as larvae when grown under conditions supporting development to adulthood for the respective single mutants. The gon-14 larval arrest is suppressed by loss of mes-2/E(Z), mes-6/ESC, or mes-4, which encodes a SET domain protein. Additionally, gon-14 affects expression of pgl-1 and lag-2, two genes regulated by the synMuv genes. We suggest that gon-14 functions with class B and class C synMuv genes to promote larval growth, in part by antagonizing MES-2,3,6/ESC-E(z) and MES-4.
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Affiliation(s)
- Michael A Chesney
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544, USA
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Perez ZN, Musingarimi P, Craig NL, Dyda F, Hickman AB. Purification, crystallization and preliminary crystallographic analysis of the Hermes transposase. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:587-90. [PMID: 16511103 PMCID: PMC1952326 DOI: 10.1107/s1744309105015721] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 05/17/2005] [Indexed: 11/10/2022]
Abstract
DNA transposition is the movement of a defined segment of DNA from one location to another. Although the enzymes that catalyze transposition in bacterial systems have been well characterized, much less is known about the families of transposase enzymes that function in higher organisms. Active transposons have been identified in many insect species, providing tools for gene identification and offering the possibility of altering the genotypes of natural insect populations. One of these active transposons is Hermes, a 2749-base-pair element from Musca domestica that encodes its own transposase. An N-terminally deleted version of the Hermes transposase (residues 79-612) has been overexpressed and purified, and crystals that diffract to 2.1 A resolution have been obtained at 277 K by the hanging-drop method.
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Affiliation(s)
- Zhanita N. Perez
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Primrose Musingarimi
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Nancy L. Craig
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
| | - Alison Burgess Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, USA
- Correspondence e-mail:
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Casola C, Marracci S, Bucci S, Ragghianti M, Mancino G, Hotz H, Uzzell T, Guex GD. A hAT-related family of interspersed repetitive elements in genomes of western Palaearctic water frogs. J ZOOL SYST EVOL RES 2004. [DOI: 10.1111/j.1439-0469.2004.00254.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ah Fong AMV, Judelson HS. The hAT -like DNA transposon DodoPi resides in a cluster of retro- and DNA transposons in the stramenopile Phytophthora infestans. Mol Genet Genomics 2004; 271:577-85. [PMID: 15098122 DOI: 10.1007/s00438-004-1004-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2003] [Accepted: 03/04/2004] [Indexed: 11/29/2022]
Abstract
A family of transposable elements belonging to the hAT group of DNA transposons is described from an oomycete, the plant pathogen Phytophthora infestans. The family, named DodoPi, was identified by studying a hotspot for retro- and DNA transposon insertions adjacent to the mating type locus. The DodoPi family comprises a small number of full-length copies, each of which is 2.7 kb long and predicted to encode a transposase-like protein consisting of 617 amino acids, and several truncated copies. Both types contain 12-bp terminal inverted repeats and are flanked by 8-bp target site duplications. Despite the detection of a DodoPi transcript and of many polymorphisms between isolates, conclusive evidence of recent transposition was not obtained. A phylogenetic analysis indicated that DodoPi was novel, with only modest similarity to some elements from plants and fungi. Relatives were detected in only some members of the genus. This is the first DNA transposon identified in the stramenopile group of eukaryotes.
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Affiliation(s)
- A M V Ah Fong
- Department of Plant Pathology, University of California, Riverside, CA 92521, USA
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12
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Atkinson PW, James AA. Germline transformants spreading out to many insect species. ADVANCES IN GENETICS 2002; 47:49-86. [PMID: 12000097 DOI: 10.1016/s0065-2660(02)47002-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The past 5 years have witnessed significant advances in our ability to introduce genes into the genomes of insects of medical and agricultural importance. A number of transposable elements now exist that are proving to be sufficiently robust to allow genetic transformation of species within three orders of insects. In particular all of these transposable elements can be used genetically to transform mosquitoes. These developments, together with the use of suitable genes as genetic markers, have enabled several genes and promoters to be transferred between insect species and their effects on the phenotype of the transgenic insect determined. Within a very short period of time, insights into the function of insect promoters in homologous and heterologous insect species are being gained. Furthermore, strategies aimed at ameliorating the harmful effects of pest insects, such as their ability to vector human pathogens, are now being tested in the pest insects themselves. We review the progress that has been made in the development of transgenic technology in pest insect species and conclude that the repertoire of transposable element-based genetic tools, long available to Drosophila geneticists, can now be applied to other insect species. In addition, it is likely that these developments will lead to the generation of pest insects that display a significantly reduced ability to transmit pathogens in the near future.
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Affiliation(s)
- Peter W Atkinson
- Department of Entomology, University of California, Riverside 92521, USA
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Michel K, O'Brochta DA, Atkinson PW. Does the proposed DSE motif form the active center in the Hermes transposase? Gene 2002; 298:141-6. [PMID: 12426102 DOI: 10.1016/s0378-1119(02)00981-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Donor cleavage and strand transfer are two functions performed by transposases during transposition of class II transposable elements. Within transposable elements, the only active center described, to date, facilitating both functions, is the so-called DDE motif. A second motif, R-K-H/K-R-H/W-Y, is found in the site-specific recombinases of the tyrosine recombinase family. While present in many bacterial insertion sequences as well as in the eukaryotic family of mariner/Tc1 elements, the DDE motif was considered absent in other classes of eukaryotic class II elements such as P, and hAT and piggyBac. Based on sequence alignments of a hobo-like element from the nematode Caenorhabditis elegans, to a variety of other hAT transposases and several members of the mariner/Tc1 group, Bigot et al. [Gene 174 (1996) 265] proposed the presence of a DSE motif in hAT transposases. In the present study we tested if each of these three residues is required for transposition of the Hermes element, a member of the hAT family commonly used for insect transformation. While D402N and E572Q mutations lead to knock-out of Hermes function, mutations S535A and S535D did not affect transposition frequency or the choice of integration sites. These data give the first experimental support that D402 and E572 are indeed required for transposition of Hermes. Furthermore, this study indicates that the active center of the Hermes transposase differs from the proposed DSE motif. It remains to be shown if other residues also form the active site of this transposase.
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Affiliation(s)
- K Michel
- Department of Entomology, University of California, Riverside, CA 92521, USA
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Galindo MI, Bigot Y, Sánchez MD, Periquet G, Pascual L. Sequences homologous to the hobo transposable element in E strains of Drosophila melanogaster. Mol Biol Evol 2001; 18:1532-9. [PMID: 11470844 DOI: 10.1093/oxfordjournals.molbev.a003939] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hobo is one of the three Drosophila melanogaster transposable elements, together with the P and I elements, that seem to have recently invaded the genome of this species. Surveys of the presence of hobo in strains from different geographical and temporal origins have shown that recently collected strains contain complete and deleted elements with high sequence similarity (H strains), but old strains lack hobo elements (E strains). Besides the canonical hobo sequences, both H and E strains show other poorly known hobo-related sequences. In the present work, we analyze the presence, cytogenetic location, and structure of some of these sequences in E strains of D. melanogaster. By in situ hybridization, we found that euchromatic hobo-related sequences were in fixed positions in all six E strains analyzed: 38C in the 2L arm; 42B and 55A in the 2R arm; 79E and 80B in the 3L arm; and 82C, 84C, and 84D in the 3R arm. Sequence comparison shows that some of the hobo-related sequences from Oregon-R and iso-1 strains are similar to the canonical hobo element, but their analysis reveals that they are substantially diverged and rearranged and cannot code for a functional transposase. Our results suggest that these ubiquitous hobo-homologous sequences are immobile and are distantly related to the modern hobo elements from D. melanogaster.
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Affiliation(s)
- M I Galindo
- Departament de Genètica, Universitat de València, Valencia, Spain
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15
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Abstract
Members of the Tourist family of miniature inverted-repeat transposable elements (MITEs) are very abundant among a wide variety of plants, are frequently found associated with normal plant genes, and thus are thought to be important players in the organization and evolution of plant genomes. In Arabidopsis, the recent discovery of a Tourist member harboring a putative transposase has shed new light on the mobility and evolution of MITEs. Here, we analyze a family of Tourist transposons endogenous to the genome of the nematode Caenorhabditis elegans (Bristol N2). One member of this large family is 7568 bp in length, harbors an ORF similar to the putative Tourist transposase from Arabidopsis, and is related to the IS5 family of bacterial insertion sequences (IS). Using database searches, we found expressed sequence tags (ESTs) similar to the putative Tourist transposases in plants, insects, and vertebrates. Taken together, our data suggest that Tourist-like and IS5-like transposons form a superfamily of potentially active elements ubiquitous to prokaryotic and eukaryotic genomes.
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Affiliation(s)
- Q H Le
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada
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Abstract
The maize transposon Activator (Ac) was the first mobile DNA element to be discovered. Since then, other elements were found that share similarity to Ac, suggesting that it belongs to a transposon superfamily named hAT after hobo from Drosophila, Ac from maize, and Tam3 from snapdragon. We addressed the structure and evolution of hAT elements by developing new tools for transposon mining and searching the public sequence databases for the hallmarks of hAT elements, namely the transposase and short terminal inverted repeats (TIRs) flanked by 8-bp host duplications. We found 147 hAT-related sequences in plants, animals, and fungi. Six conserved blocks could be identified in the transposase of most hAT elements. A total of 41 hAT sequences were flanked by TIRs and 8-bp host duplications and, out of these, 34 sequences had TIRs similar to the consensus determined in this work, suggesting that they are active or recently active transposons. Phylogenetic analysis and clustering of hAT sequences suggest that the hAT superfamily is very ancient, probably predating the plant-fungi-animal separation, and that, unlike previously proposed, there is no evidence that horizontal gene transfer was involved in the evolution of hAT elements.
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Affiliation(s)
- E Rubin
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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Harrison PM, Echols N, Gerstein MB. Digging for dead genes: an analysis of the characteristics of the pseudogene population in the Caenorhabditis elegans genome. Nucleic Acids Res 2001; 29:818-30. [PMID: 11160906 PMCID: PMC30377 DOI: 10.1093/nar/29.3.818] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pseudogenes are non-functioning copies of genes in genomic DNA, which may either result from reverse transcription from an mRNA transcript (processed pseudogenes) or from gene duplication and subsequent disablement (non-processed pseudogenes). As pseudogenes are apparently 'dead', they usually have a variety of obvious disablements (e.g., insertions, deletions, frameshifts and truncations) relative to their functioning homologs. We have derived an initial estimate of the size, distribution and characteristics of the pseudogene population in the Caenorhabditis elegans genome, performing a survey in 'molecular archaeology'. Corresponding to the 18 576 annotated proteins in the worm (i.e., in Wormpep18), we have found an estimated total of 2168 pseudogenes, about one for every eight genes. Few of these appear to be processed. Details of our pseudogene assignments are available from http://bioinfo.mbb.yale.edu/genome/worm/pseudogene. The population of pseudogenes differs significantly from that of genes in a number of respects: (i) pseudogenes are distributed unevenly across the genome relative to genes, with a disproportionate number on chromosome IV; (ii) the density of pseudogenes is higher on the arms of the chromosomes; (iii) the amino acid composition of pseudogenes is midway between that of genes and (translations of) random intergenic DNA, with enrichment of Phe, Ile, Leu and Lys, and depletion of Asp, Ala, Glu and Gly relative to the worm proteome; and (iv) the most common protein folds and families differ somewhat between genes and pseudogenes-whereas the most common fold found in the worm proteome is the immunoglobulin fold and the most common 'pseudofold' is the C-type lectin. In addition, the size of a gene family bears little overall relationship to the size of its corresponding pseudogene complement, indicating a highly dynamic genome. There are in fact a number of families associated with large populations of pseudogenes. For example, one family of seven-transmembrane receptors (represented by gene B0334.7) has one pseudogene for every four genes, and another uncharacterized family (represented by gene B0403.1) is approximately two-thirds pseudogenic. Furthermore, over a hundred apparent pseudogenic fragments do not have any obvious homologs in the worm.
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Affiliation(s)
- P M Harrison
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, PO Box 208114, New Haven, CT 06511-8114, USA
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Pontecorvo G, De Felice B, Carfagna M. A novel repeated sequence DNA originated from a Tc1-like transposon in water green frog Rana esculenta. Gene 2000; 261:205-10. [PMID: 11167006 DOI: 10.1016/s0378-1119(00)00539-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have identified and characterized a highly repetitive family, called R.e./Tc1 in the genome of the green water frog Rana esculenta. This family consists of tandemly repeated sequences, localized at the centromeric regions of chromosomes as shown by Southern blot and 'in situ' hybridization. The repeat unit contains a residue of a Tc1-like transposon by Haematobia irritans fly, bordered by two short direct repeats of 9 bp. Tc1 remnant lays near a sequence identical to Homo sapiens Werner syndrome gene stretch. These sequence data suggest that R.e./Tc1 element was probably originated from a transposition event and a duplication via DNA mechanism of the R.e./Tc1 unit that could give rise to the observed tandem array.
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Affiliation(s)
- G Pontecorvo
- Department of Life Sciences, II University of Naples, Via Vivaldi 43, 81100, Caserta, Italy.
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Koga A, Shimada A, Shima A, Sakaizumi M, Tachida H, Hori H. Evidence for recent invasion of the medaka fish genome by the Tol2 transposable element. Genetics 2000; 155:273-81. [PMID: 10790401 PMCID: PMC1461052 DOI: 10.1093/genetics/155.1.273] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tol2 is a transposable element of the terminal-inverted-repeat class, residing in the genome of the medaka fish Oryzias latipes. The genus Oryzias contains more than 10 species for which phylogenetic relationships have previously been estimated. To infer the history of Tol2 in this genus we performed genomic Southern blots and PCR analyses of 10 of the species. It was revealed that Tol2 occurs in 2 of the 10 species (O. curvinotus and O. latipes) and that the length and the restriction map structure of Tol2 are identical in the two cases. Further, sequencing analysis revealed an extremely low level of divergence compared with that in a nuclear gene. These results suggest recent incorporation of Tol2 into one or both of the two species, implying horizontal transfer of Tol2 from one species to the other or into them both from a common source.
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Affiliation(s)
- A Koga
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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Handler AM, Gomez SP. A new hobo, Ac, Tam3 transposable element, hopper, from Bactrocera dorsalis is distantly related to hobo and Ac. Gene 1997; 185:133-5. [PMID: 9034324 DOI: 10.1016/s0378-1119(96)00658-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A new transposable element from the hobo, Ac, Tam3 transposon family was isolated as a genomic clone from the oriental fruit fly, Bactrocera dorsalis. It is approximately 3.1 kb in length with 19-bp inverted terminal repeat sequences having a single mismatch. Though sharing several amino acid sequence identities with other hAT elements, it is distantly related to both hobo and Ac. Among hAT elements thus far described in insects, it is apparently the most distantly related to hobo.
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Affiliation(s)
- A M Handler
- Agricultural Research Service, US Department of Agriculture, Gainesville, FL 32608, USA.
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