Modified Transposases for Site-Directed Insertion of Transgenes

Abstract

Cut and paste DNA transposons are widely used to stably integrate DNA into a wide variety of organisms. They can integrate DNA with high ef fi ciency, provide long lasting expression of inserted transgenes, and avoid some of the safety concerns of viral gene delivery systems. One of the chief disadvantages of transposons for gene therapy and other gene delivery applications is that the site of insertion cannot be chosen. This can lead to poor expression of the integrated gene if it is inserted into a region of heterochromatin, or to undesirable insertional mutagenesis of the host cell if it integrates in an important gene. Three main strategies have been used to direct transposon insertions to speci fi c locations: (1) modifying the transposase by fusing it to a DNA binding domain, (2) tethering the transposase protein to the desired target site, or (3) tethering the transposon DNA to the target site using appropriate fusion proteins. Here we review progress with these strategies in bacteria, fi sh, insect and mammalian systems.

Vast potential for using the piggyBac transposon to engineer transgenic plants at specific genomic locations

“…6 Any segment of DNA placed between the transposon inverted repeat sequences can be moved from a donor to a target location by the transposase, although there may be 7 The insertion specificity of some DNA transposons has been modified by fusing specific DNA binding domains to the transposase protein (or by tethering the transposon DNA to specific targets using bifunctional DNA binding proteins). 8 Most of these experiments were completed in organisms besides plants. However, recent developments with an insect DNA transposase, piggyBac, suggest that engineered versions of piggyBac transposase could one day insert transgenes into plant chromosomes with high specificity.…”