Target site choice is a complex and poorly understood aspect of DNA transposition despite its importance in rational transposon-mediated gene delivery. Thoughmost transposons choose target sites essentially randomly or with some slight sequence or structural preferences, insertion sequence IS608 from Helicobacter pylori, which transposes using single-stranded DNA, always inserts just 3′ of a TTAC tetranucleotide. Our results from studies on the IS608 transposition mechanism demonstrated that the transposase recognizes its target site by co-opting an internal segment of transposon DNA and utilizes it for specific recognition of the target sites through base-pairing. This suggested a way to redirect IS608 transposition to novel target sites. As we demonstrate here, we can now direct insertions in a predictable way into a variety of different chosen target sequences, both in vitro and in vivo.
This chapter presents an analysis of the organization and distribution of the IS200/IS605 family of insertion sequences (IS). Members of this family are widespread in both bacteria and archaea. They are unusual because they use obligatory single-strand DNA intermediates, which distinguishes them from classical IS. We summarize studies of the experimental model systems IS608 (from Helicobacter pylori) and ISDra2 (from Deinococcus radiodurans) and present biochemical, genetic, and structural data that describe their transposition pathway and the way in which their transposase (an HuH rather than a DDE enzyme) catalyzes this process. The transposition of IS200/IS605 family members can be described as a "Peel-and-Paste" mechanism. We also address the probable domestication of IS200/IS605 family transposases as enzymes involved in multiplication of repeated extragenic palindromes and as potential homing endonucleases in intron-IS chimeras.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.