Retrotransposons that maintain chromosome ends

Retrotransposons that maintain chromosome ends.

Reverse transcriptases have shaped genomes in many ways. A remarkable example of this shaping is found on telomeres of the genus Drosophila, where retrotransposons have a vital role in chromosome structure. Drosophila lacks telomerase; instead, three telomere-specific retrotransposons maintain chromosome ends. Repeated transpositions to chromosome ends produce long head to tail arrays of these ...

Insertion of Retrotransposons at Chromosome Ends: Adaptive Response to Chromosome Maintenance

The telomerase complex is a specialized reverse transcriptase (RT) that inserts tandem DNA arrays at the linear chromosome ends and contributes to the protection of the genetic information in eukaryotic genomes. Telomerases are phylogenetically related to retrotransposons, encoding also the RT activity required for the amplification of their sequences throughout the genome. Intriguingly the tel...

Gag proteins of the two Drosophila telomeric retrotransposons are targeted to chromosome ends

Drosophila telomeres are formed by two non-LTR retrotransposons, HeT-A and TART, which transpose only to chromosome ends. Successive transpositions of these telomeric elements yield arrays that are functionally equivalent to the arrays generated by telomerase in other organisms. In contrast, other Drosophila non-LTR retrotransposons transpose widely through gene-rich regions, but not to ends. T...

Evolution of diverse mechanisms for protecting chromosome ends by Drosophila TART telomere retrotransposons.

The retrotransposons HeT-A, TART, and TAHRE, which maintain Drosophila telomeres, transpose specifically onto chromosome ends to form long arrays that extend the chromosome and compensate for terminal loss. Because they transpose by target-primed reverse transcription, each element is oriented so that its 5' end serves as the extreme end of the chromosome until another element transposes to occ...

Evolution of diverse mechanisms for protecting chromosome ends by the Drosophila TART telomere retrotransposons