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Mobile Genetic Elements

Nicolas Carraro, Nicolas Rivard, Vincent Burrus, Daniela Ceccarelli
Mobile genetic elements are near ubiquitous DNA segments that revealed a surprising variety of strategies for their propagation among prokaryotes and between eukaryotes. In bacteria, conjugative elements were shown to be key drivers of evolution and adaptation by efficiently disseminating genes involved in pathogenicity, symbiosis, metabolic pathways, and antibiotic resistance. Conjugative plasmids of the incompatibility groups A and C (A/C) are important vehicles for the dissemination of antibiotic resistance and the consequent global emergence and spread of multi-resistant pathogenic bacteria...
2017: Mobile Genetic Elements
Lavanya Rishishwar, Lu Wang, Evan A Clayton, Leonardo Mariño-Ramírez, John F McDonald, I King Jordan
Recent technological developments-in genomics, bioinformatics and high-throughput experimental techniques-are providing opportunities to study ongoing human transposable element (TE) activity at an unprecedented level of detail. It is now possible to characterize genome-wide collections of TE insertion sites for multiple human individuals, within and between populations, and for a variety of tissue types. Comparison of TE insertion site profiles between individuals captures the germline activity of TEs and reveals insertion site variants that segregate as polymorphisms among human populations, whereas comparison among tissue types ascertains somatic TE activity that generates cellular heterogeneity...
2017: Mobile Genetic Elements
Mikako Ueno, Tadashi Okamura, Masayoshi Mishina, Yukihito Ishizaka
BACKGROUND: Retrotransposition of long interspersed nuclear element-1 (L1-RTP) is proposed to contribute to central nervous system (CNS) plasticity by inducing mosaicism of neuronal cells. Clinical studies have identified increased L1 copy numbers in the brains of patients with psychiatric disorders. These observations implicate that L1-RTP is important for neurogenesis and that its deregulation represents a risk factor for mental disorders. However, no supportive evidence is available for understanding the importance of L1-RTP in CNS function...
July 2016: Mobile Genetic Elements
Joshua P Ramsay, Stephen M Kwong, Riley J T Murphy, Karina Yui Eto, Karina J Price, Quang T Nguyen, Frances G O'Brien, Warren B Grubb, Geoffrey W Coombs, Neville Firth
The horizontal gene transfer facilitated by mobile genetic elements impacts almost all areas of bacterial evolution, including the accretion and dissemination of antimicrobial-resistance genes in the human and animal pathogen Staphylococcus aureus. Genome surveys of staphylococcal plasmids have revealed an unexpected paucity of conjugation and mobilization loci, perhaps suggesting that conjugation plays only a minor role in the evolution of this genus. In this letter we present the DNA sequences of historically documented staphylococcal conjugative plasmids and highlight that at least 3 distinct and widely distributed families of conjugative plasmids currently contribute to the dissemination of antimicrobial resistance in Staphylococcus...
July 2016: Mobile Genetic Elements
Claiborne M Christian, Kristine J Kines, Victoria P Belancio
The Long Interspersed Element 1 (LINE1 or L1) ORF2 protein (ORF2p) can cause DNA damage through the activity of its endonuclease domain (EN). The DNA double-strand breaks (DSB) introduced by the ORF2p EN have the potential to be mutagenic. Previously, our lab has shown that ORF2p fragments containing the EN domain could be expressed in mammalian cells and have variable cytotoxicity. Inclusion of the ORF2p sequence C-terminal to the EN domain in these fragments both reduced the cytotoxicity of these fragments and increased their presence in the nucleus as detected by Western blot analysis...
July 2016: Mobile Genetic Elements
Douglas R Deutsch, Bryan Utter, Vincent A Fischetti
Staphylococcus aureus is a major clinically important pathogen with well-studied phage contributions to its virulence potential. In this commentary, we describe our method to enrich and sequence stealth extra-chromosomal DNA elements in the bacterial cell, allowing the identification of novel extra-chromosomal prophages in S. aureus clinical strains. Extra-chromosomal sequencing is a useful and broadly applicable tool to study bacterial genomics, giving a temporal glance at the extra-chromosomal compartment of the cell and allowing researchers to uncover lower-copy plasmidial elements (e...
July 2016: Mobile Genetic Elements
Joseph S Murray, Elaina H Murray
Genes of the major histocompatibility complex (MHC; also called HLA in human) are polymorphic elements in the genomes of sharks to humans. Class-I and class-II MHC loci appear responsible for much of the genetic linkage to myriad disease states via the capacity to bind short (~8-15 a.a.) peptides of a given pathogen's proteome, or in some cases, the altered proteomes of cancerous cells, and even (in autoimmunity) certain nominal 'self' peptides (Janeway, 2004).(1) Unfortunately, little is known about how the canonical structure of the MHC-I/-II peptide-presenting gene evolved, particularly since beyond ~500 Mya (sharks) no paralogs exist...
May 2016: Mobile Genetic Elements
Irene Munk Pedersen, Dimitrios G Zisoulis
Transposable elements, the class of mobile DNA sequences that change their copies or positions within the genome have an ever increasing role in shaping the genetic and evolutionary landscape. Approximately half of the mammalian genome is composed of repetitive elements, including LINE-1 (L1) elements. Because of their ability to "copy and paste" into other regions of the genome, their activation represent an opportunity as well as a threat, as L1-induced mutations results in genomic instability and plasticity...
May 2016: Mobile Genetic Elements
Tomoyuki Honda, Keizo Tomonaga
Vertebrate genomes contain many virus-related sequences derived from both retroviruses and non-retroviral RNA and DNA viruses. Such non-retroviral RNA sequences are possibly produced by reverse-transcription and integration of viral mRNAs of ancient RNA viruses using retrotransposon machineries. We refer to this process as transcript reversion. During an ancient bornavirus infection, transcript reversion may have left bornavirus-related sequences, known as endogenous bornavirus-like nucleoproteins (EBLNs), in the genome...
May 2016: Mobile Genetic Elements
Ellie Harrison, Calvin Dytham, James P J Hall, David Guymer, Andrew J Spiers, Steve Paterson, Michael A Brockhurst
Conjugative plasmids play a vital role in bacterial adaptation through horizontal gene transfer. Explaining how plasmids persist in host populations however is difficult, given the high costs often associated with plasmid carriage. Compensatory evolution to ameliorate this cost can rescue plasmids from extinction. In a recently published study we showed that compensatory evolution repeatedly targeted the same bacterial regulatory system, GacA/GacS, in populations of plasmid-carrying bacteria evolving across a range of selective environments...
May 2016: Mobile Genetic Elements
Jessica M Tucker, David J Garfinkel
Ty1 is a long terminal repeat (LTR) retrotransposon belonging to the Ty1/copia family and is present in up to 32 full-length copies in Saccharomyces. Like retroviruses, Ty1 contains GAG and POL genes, LTRs, and replicates via an RNA intermediate within a virus-like particle (VLP). Although Ty1 retrotransposition is not infectious, uncontrolled replication can lead to detrimental effects on the host genome, including insertional mutagenesis and chromosomal rearrangements. Ty1 copy number control (CNC) limits replication and is mediated through a self-encoded protein called p22...
March 2016: Mobile Genetic Elements
Guilherme B Dias, Pedro Heringer, Gustavo C S Kuhn
Although Helitrons were discovered 15 y ago, they still represent an elusive group of transposable elements (TEs). They are thought to transpose via a rolling-circle mechanism, but no transposition assay has yet been conducted. We have recently characterized a group of Helitrons in Drosophila, named DINE-TR1, that display interesting features, including pronounced enrichment at β-heterochromatin, multiple tandem insertions (TIs) of the entire TE, and that experienced at least 2 independent expansion events of its internal tandem repeats (TRs) in distant Drosophila lineages...
March 2016: Mobile Genetic Elements
Katarzyna Pachulska-Wieczorek, Leszek Błaszczyk, Julita Gumna, Yuri Nishida, Agniva Saha, Marcin Biesiada, David J Garfinkel, Katarzyna J Purzycka
The long terminal repeat (LTR) and non-LTR retrotransposons comprise approximately half of the human genome, and we are only beginning to understand their influence on genome function and evolution. The LTR retrotransposon Ty1 is the most abundant mobile genetic element in the S. cerevisiae reference genome. Ty1 replicates via an RNA intermediate and shares several important structural and functional characteristics with retroviruses. However, unlike retroviruses Ty1 retrotransposition is not infectious. Retrotransposons integrations can cause mutations and genome instability...
March 2016: Mobile Genetic Elements
Eduard Kejnovsky, Edward N Trifonov
Acytota is a kingdom of life covering satellites, plasmids, transposable elements, viroids and viruses, all outside the conventional tree of life but satisfying most life definitions. This review focuses on some aspects of Acytota, their "genomes" and life styles, the dominance of transposable elements and their evolutionary influence on other life forms in order to vindicate the Acytota as a life kingdom no more polyphyletic than other kingdoms and its members no more parasitic than other life forms.
March 2016: Mobile Genetic Elements
Peter Arensburger, Benoît Piégu, Yves Bigot
Transposable element (TE) science has been significantly influenced by the pioneering ideas of David Finnegan near the end of the last century, as well as by the classification systems that were subsequently developed. Today, whole genome TE annotation is mostly done using tools that were developed to aid gene annotation rather than to specifically study TEs. We argue that further progress in the TE field is impeded both by current TE classification schemes and by a failure to recognize that TE biology is fundamentally different from that of multicellular organisms...
2016: Mobile Genetic Elements
Suhartono Suhartono, Mary Savin
A conjugation assay was used to determine the effects of phenotypic resistance to one to up to 5 antibiotics, sampling site of origin, presence or absence of class 1 and/or class 2 integrase (intI) genes (intI1 and intI2), and the number of sulfamethoxazole resistance (sul) and trimethoprim resistance (dfr) genes on the transfer frequencies of plasmids from environmental, antibiotic-resistant Escherichia coli. Of 51 sulfamethoxazole and trimethoprim-resistant E. coli isolates conferring at least one mob gene (mobP51, mobF11, mobF12, mobQ11, mobQ12 , or mobQu ), 38 produced transconjugants with an overall mean frequency of 1...
2016: Mobile Genetic Elements
Cecile Monat, Ndomassi Tando, Christine Tranchant-Dubreuil, Francois Sabot
Automatic classification of LTR retrotransposons is a big challenge in the area of massive genomics. Many tools were developed to detect them but automatic classification is somehow challenging. Here we propose a simple approach, LTRclassifier, based on HMM recognition followed by BLAST analyses (i) to classify plant LTR retrotransposons in their respective superfamily, and (ii) to provide automatically a basic functional annotation of these elements. The method was tested on various TE databases, and shown to be robust and fast...
2016: Mobile Genetic Elements
Tobias Mourier
Circular DNAs are extra-chromosomal fragments that become circularized by genomic recombination events. We have recently shown that yeast LTR elements generate circular DNAs through recombination events between their flanking long terminal repeats (LTRs). Similarly, circular DNAs can be generated by recombination between LTRs residing at different genomic loci, in which case the circular DNA will contain the intervening sequence. In yeast, this can result in gene copy number variations when circles contain genes and origins of replication...
2016: Mobile Genetic Elements
Mohd Faheem Khan, Kush Shrivastava, Rebeka Sinha, Virendra Kumar, A K Jaitly
Retrotransposons play significant role in genome remodelling of T. brucei and about 5% of its genome consists of retrotransposons including INGI/RIME elements. INGI is one of the dispersed repetitive elements in T. brucei genome which is found distributed throughout all the chromosomes. SLACS (Spliced Leader Associated Conserved Sequence) however, is more conserved in its nature and lacks the typical poly-distributional pattern of LINE like transposons. We have found total 589 copies of these TEs with only 17...
2016: Mobile Genetic Elements
Vandan Shah, Jin Ryoun Kim
Protein insertional fusion and circular permutation are 2 promising protein engineering techniques for creating integrated functionalities and sequence diversity of a protein, respectively. Finding insertion locations for protein insertional fusion and new termini for circular permutation through a rational approach is not always straightforward, especially, for proteins without detailed structural knowledge. On the contrary, a combinatorial approach facilitates a comprehensive search to evaluate all potential insertion sites and new termini locations...
2016: Mobile Genetic Elements
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