DNA sequences {transposon, DNA} can excise themselves and then insert at other genome locations {transposition, DNA}|. Transposons code for enzymes that recognize DNA splice sites.
methylation
Methylation inactivates transposons.
bacteria
Bacteria have Tn3 and Tn10 transposons with DNA insertion sequences (IS). Tn3 transposons code enzymes that act at transposon-resolvase sites to allow recombination, so they copy themselves, place copies at new sites, and leave originals.
bacteria: Agrobacterium
Agrobacterium infects plants with Ti plasmid.
yeast
Yeast has Ty elements, whose delta-element direct repeats have promoters. Ty elements contain reverse transcriptase.
Yeast MAT genes have mating-type alleles. Yeasts have two mating types, a and alpha. After mating, mating type changes to opposite mating type, as HO endonuclease cuts MAT site. a-gene and alpha-gene copies are far from MAT sites. Copies are templates to reconstruct MAT site as opposite mating type {gene conversion} {replicative transposition}.
Yeast sterile (STE) genes code for a and alpha pheromones, which stop cell growth and change cell shape. Pheromones combine both mating types to form diploids, causing yeast to mate. STE proteins are G-protein subunits (STE4) (STE18), protein kinases, and transcription factors (STE12). STE proteins (STE2) (STE3) can bind factors.
maize
Maize has Ac and Ds transposable elements.
retrovirus
Retroviruses have direct repeats with promoters and contain reverse transcriptase to allow transposition.
trypanosome
Trypanosomes use gene conversion to vary surface glycoproteins (VSG).
fruitfly
Drosophila have P elements. Drosophila have copia elements, which have direct repeats with promoters.
Biological Sciences>Genetics>Post-Transcription>Transposition
4-Genetics-Post-Transcription-Transposition
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Date Modified: 2022.0224