IS1294, a DNA Element That Transposes by RC Transposition

Tavakoli, Norma P.; Comanducci, Antonella; Dodd, Helen M.; Lett, Marie‐Claire; Albiger, Barbara; Bennett, Peter M.

doi:10.1006/plas.1999.1460

Cited by 84 publications

(88 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rather than by cut and paste, these DNA elements are proposed to move through replication and strand replacement. This mode of propagation, called rolling circle transposition, has been reported previously in some insertional sequence groups of transposable elements in prokaryotes (Tavakoli et al, 2000), bacterial plasmids (Khan, 2000), and the circular single-stranded DNA of plant geminiviruses (Rigden et al, 1996).…”

Section: Introductionsupporting

confidence: 64%

The Maize Genome Contains a Helitron Insertion

et al. 2003

View full text Add to dashboard Cite

The maize mutation sh2-7527 was isolated in a conventional maize breeding program in the 1970s. Although the mutant contains foreign sequences within the gene, the mutation is not attributable to an interchromosomal exchange or to a chromosomal inversion. Hence, the mutation was caused by an insertion. Sequences at the two Sh2 borders have not been scrambled or mutated, suggesting that the insertion is not caused by a catastrophic reshuffling of the maize genome. The insertion is large, at least 12 kb, and is highly repetitive in maize. As judged by hybridization, sorghum contains only one or a few copies of the element, whereas no hybridization was seen to the Arabidopsis genome. The insertion acts from a distance to alter the splicing of the sh2 pre-mRNA. Three distinct intron-bearing maize genes were found in the insertion. Of most significance, the insertion bears striking similarity to the recently described DNA helicase-bearing transposable elements termed Helitrons . Like Helitrons , the inserted sequence of sh2-7527 is large, lacks terminal repeats, does not duplicate host sequences, and was inserted between a host dinucleotide AT. Like Helitrons , the maize element contains 5 TC and 3 CTRR termini as well as two short palindromic sequences near the 3 terminus that potentially can form a 20-bp hairpin. Although the maize element lacks sequence information for a DNA helicase, it does contain four exons with similarity to a plant DEAD box RNA helicase. A second Helitron insertion was found in the maize genomic database. These data strongly suggest an active Helitron in the present-day maize genome.

show abstract

Section: Introductionsupporting

confidence: 64%

The Maize Genome Contains a Helitron Insertion

et al. 2003

View full text Add to dashboard Cite

show abstract

“…Some of the maize Helitrons were found to produce chimeric transcripts that fused fragments of genes transduced from different loci, suggesting that they could mediate the formation of new genes through exon shuffling (21,22). Transduction of adjacent sequences by bacterial RC insertion sequences has been shown to occur experimentally at frequencies ranging from 1% to 10% (16). Furthermore, bacterial RC transposons are associated with a plethora of virulence and antibiotic resistance genes and are thought to be involved in the mobilization of these factors among strains and species (17,38).…”

Section: Discussionmentioning

confidence: 99%

“…Helitrons are distinguished from other classes of TEs by their overall structure and by the putative enzymatic activities encoded by autonomous copies (11). Helitrons share structural and sequence similarities with a disparate group of prokaryotic mobile elements and single-stranded DNA (ssDNA) viruses that use RC replication, a process that involves the nicking, displacement, and ligation of an ssDNA intermediate (15)(16)(17)(18). Helitrons are poorly characterized TEs in eukaryotes, but they make up Ϸ2% of the small genomes of Arabidopsis thaliana and Caenorhabidits elegans (11).…”

mentioning

confidence: 99%

Massive amplification of rolling-circle transposons in the lineage of the bat Myotis lucifugus

Pritham

Feschotte

2007

Proc. Natl. Acad. Sci. U.S.A.

154

195

View full text Add to dashboard Cite

Rolling-circle (RC) transposons, or Helitrons, are a newly recognized group of eukaryotic transposable elements abundant in the genomes of plants, invertebrates, and zebrafish. We provide evidence for the colonization of a mammalian genome by Helitrons, which has not been reported previously. We identified and characterized two families of Helitrons in the little brown bat Myotis lucifugus. The consensus sequence for the first family, HeliBat1, displays the hallmarks of an autonomous Helitron, including coding capacity for an Ϸ1,500-aa protein with an RC replication motif and a region related to the SF1 superfamily of DNA helicases. The HeliBatN1 family is a nonautonomous Helitron family that is only distantly related to HeliBat1. The two HeliBat families have attained high copy numbers (Ϸ15,000 and > 100,000 copies, respectively) and make up at least Ϸ3% of the M. lucifugus genome. Sequence divergence and cross-species analyses indicate that both HeliBat families have amplified within the last Ϸ30 -36 million years and are restricted to the lineage of vesper bats. We could not detect the presence of Helitrons in any other order of placental mammals, despite the broad representation of these taxa in the databases. We describe an instance of HeliBat-mediated transduction of a host gene fragment that was subsequently dispersed in Ϸ1,000 copies throughout the M. lucifugus genome. Given the demonstrated propensity of RC transposons to mediate the duplication and shuffling of host genes in bacteria and maize, it is tempting to speculate that the massive amplification of Helitrons in vesper bats has influenced the evolutionary trajectory of these mammals.Chiroptera ͉ Helitron ͉ horizontal transfer ͉ mammalian genome ͉ transposable elements T he largest fraction of most eukaryotic genomes is made up of interspersed repetitive DNA. Transposable elements (TEs) represent the major type of interspersed repeats and often constitute the single largest component of the genetic material. For example, approximately half of the human genome is made of TEs (1), and at least 60% of the maize genome is occupied by TEs (2). There is evidence that TEs have contributed profoundly to shaping eukaryotic genomes through their movement and amplification (for review, see refs. 3-5).Mammalian TEs described so far fall within three types: nonlong-terminal repeat (non-LTR) retrotransposons, retroviral-like (LTR) elements, and DNA transposons. The non-LTR retrotransposons are, by far, the most abundant type of TEs in the genomes of human, mouse, rat, and dog (1, 6-8). In humans, two predominant families of non-LTR retrotransposons (Alu and L1) account for more than one-fourth of the genome and have been major players in the structural genomic evolution of humans and other primates (9, 10). Much less is known about the nature and impact of TEs in the genome of other mammalian lineages.We report on the discovery of rolling-circle (RC) transposons, also known as Helitrons, in the genome of the little brown bat, Myotis lucifugus. Although Helitron...

show abstract

“…The majority of eukaryotic transposases belong to the DDE class, named after the highly conserved Asp (D), Asp (D), and Glu (E) amino acid residues, which belong to the catalytic core (4,5). It has been suggested (6)(7)(8) that the bacterial transposons IS91, IS801, and IS1294 form an exotic family of prokaryotic rolling-circle (RC) transposons that do not belong to the DDE class, as they transpose via RC replication (RCR). These transposons share common 5Ј-AY and GTTC-3Ј termini, do not possess TIRs, and do not generate TSDs.…”

mentioning

confidence: 99%

“…These transposons share common 5Ј-AY and GTTC-3Ј termini, do not possess TIRs, and do not generate TSDs. They encode only one protein, similar to the replication initiator proteins (Rep) from known RC replicons (6)(7)(8)(9). There are three groups of episomal replicons using RCR: circular single-stranded DNA (ssDNA) bacteriophages (10), plasmids of bacteria or archaea (11), and geminiviruses (circular ssDNA viruses replicating in plant cells) (12).…”

mentioning

confidence: 99%

Rolling-circle transposons in eukaryotes

Kapitonov

Jurka²

2001

Proc. Natl. Acad. Sci. U.S.A.

456

541

View full text Add to dashboard Cite

All eukaryotic DNA transposons reported so far belong to a single category of elements transposed by the so-called ''cut-and-paste'' mechanism. Here, we report a previously unknown category of eukaryotic DNA transposons, Helitron, which transpose by rollingcircle replication. Autonomous Helitrons encode a 5 -to-3 DNA helicase and nuclease͞ligase similar to those encoded by known rolling-circle replicons. Helitron-like transposons have conservative 5 -TC and CTRR-3 termini and do not have terminal inverted repeats. They contain 16-to 20-bp hairpins separated by 10 -12 nucleotides from the 3 -end and transpose precisely between the 5 -A and T-3 , with no modifications of the AT target sites. Together with their multiple diverged nonautonomous descendants, Helitrons constitute Ϸ2% of both the Arabidopsis thaliana and Caenorhabditis elegans genomes and also colonize the Oriza sativa genome. Sequence conservation suggests that Helitrons continue to be transposed.

show abstract

IS1294, a DNA Element That Transposes by RC Transposition

Cited by 84 publications

References 71 publications

The Maize Genome Contains a Helitron Insertion

The Maize Genome Contains a Helitron Insertion

Massive amplification of rolling-circle transposons in the lineage of the bat Myotis lucifugus

Rolling-circle transposons in eukaryotes

Contact Info

Product

Resources

About