Transposable elements (TEs), also known as transposable elements - often referred to as "jumping genes" - are DNA segments that can move within the genome, i.e. change their position ("transposition"). In many organisms, they make up a significant proportion of the genome (around 45% in humans). In their entirety, they are referred to as transposons. TEs can copy or cut and paste themselves into new genome sites. TEs are key drivers of genetic variation, genome size and evolution - but are also potential sources of mutations.
Transposable elements
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Classes of transposable elements
1. class I - retrotransposons ("copy and paste") - transposition via RNA intermediate step.
- Transcription into RNA
- Reverse transcription to DNA (by reverse transcriptase)
- Integration at a new site
- Subtypes:
- LTR retrotransposons (similar to retroviruses)
- LINEs (Long Interspersed Nuclear Elements, e.g. LINE-1 in humans)
- SINEs (Short Interspersed Nuclear Elements, e.g. aluminum elements)
Class II - DNA transposons ("cut and paste")
- Direct cutting and pasting of the DNA element. DNA transposons often require the enzyme "transposase", which catalyzes the movement.
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Mobility: Transposable elements (TEs) can move from one genome position to another.
Self-replicating: Many TEs can make copies of themselves so that their number in the genome can increase.
Mutagenic effect: By inserting TEs into or near genes, they can alter their function or regulation.
Biological significance of TEs:
- Evolution:
- Create genetic diversity and new regulatory networks.
- Can contribute new exons, promoters or enhancers.
- Genome architecture:
- Responsible for large parts of repetitive DNA.
- Contribute to chromosome structure and recombination.
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Insertions can disrupt genes (e.g. hemophilia, Duchenne muscular dystrophy).
Activity of TEs can be increased in cancer cells.
Cells suppress TE activity by:
- DNA methylation
- Histone modifications
- RNA interference (piRNAs, siRNAs)
LiteratureThis section has been translated automatically.
- Babakhani S et al. (2018) Transposons: the agents of antibiotic resistance in bacteria. J Basic Microbiol 58:905-917.
- Frost LS et al. (2005) Mobile genetic elements: the agents of open source evolution. Nat Rev Microbiol 3:722-32
- Ghaly TM et al. (2020) A Novel Family of Acinetobacter Mega-Plasmids Are Disseminating Multi-Drug Resistance Across the Globe While Acquiring Location-Specific Accessory Genes. Front Microbiol 11:605952.
- Kumar A (2020) Jump around: transposons in and out of the laboratory. F1000Res 24: F1000 Faculty Rev-135.
- McClintock B (1950): The origin and behavior of mutable loci in maize. In: Proceedings of the National Academy of Sciences 36: 344-355.
- Raiz J et al. (2012): The non-autonomous retrotransposon SVA is trans-mobilized by the human LINE-1 protein machinery.Nucleic Acids Res 40: 1666-1683.