Different DNA repair pathways are required following excision and integration of the DNA cut & paste transposon piggyBat in Saccharomyces cerevisiae.

Abstract

The movement of transposable elements from place to place in a genome requires both element-encoded and host-encoded factors. In DNA cut & paste transposition, the element-encoded transposase performs the DNA breakage and joining reactions that excise the element from the donor site and integrate it into the new insertion site. Host factors can influence many aspects of transposition. Notably, host DNA repair factors mediate the regeneration of intact duplex DNA necessary after transposase action by repairing the double strand break in the broken donor backbone, from which the transposon has excised, and repairing the single strand gaps that flank the newly inserted transposon. We have exploited the ability of the mammalian transposon piggyBat, a member of the piggyBac superfamily, to transpose in Saccharomyces cerevisiae and used the yeast single gene deletion collection to screen for genes encoding host factors involved in piggyBat transposition. piggyBac transposition is distinguished by the fact that piggyBac elements insert into TTAA target sites and also that the donor backbone is restored to its pre-transposon sequence after transposon excision, that is, excision is precise. We have found that repair of the broken donor backbone requires the non-homologous end-joining repair pathway (NHEJ). By contrast, NHEJ is not required for DNA repair at the new insertion site. Thus multiple DNA repair pathways are required for piggyBac transposition.