The Take and Give Between Retrotransposable Elements and their Hosts

Retrotransposons mobilize via RNA. intermediates and usually carry with them the agent of their mobility, reverse transcriptase. Retrotransposons are streamlined, and therefore rely oil host factors to proliferate. However, retrotransposons are exposed to cellular forces that block their paths. For this review, we have selected for our focus elements from among target-primed (TP) retrotransposons, also called non-LTR retrotransposons, and extrachromosomally-primed (EP) retrotransposons, also called LTR retrotransposons. The TP retrotransposons considered here are group II introns, LINEs and SINEs, whereas the EP elments considered are the Ty and Tf retrotransposons, with a brief comparison to retroviruses. Recurring themes for these elements, in host ranging froth bacteria to humans, are tie-ills of the retrotransposons to RNA metabolism, DNA. replication and repair, and cellular stress. Likewise, there are parallels among host-cell defenses to combat rampant retrotransposon spread. The interactions between the retrotransposon and the host, and their coevolution to balance the tension between retrotransposon proliferation and host survival, from the basis of this review.