Genomic engineering is based on the stable integration of DNA into the genome of a living cell.
The introduced DNA can be either randomly, site specifically or homologously recombined into the genome, or maintained as an episome. In the first applications of this technology, phenotype was altered upon DNA introduction. We are developing strategies whereby the phenotypic alteration can be induced at a chosen time after DNA introduction. SSRs of the integrase class such as FLP, from the 2m episome of S. cereviseae, Cre, from the E.coli P1 phage, and R from Z. rouxii are able to mediate precise and conservative recombination between their binding sites. These three proteins share overall similarity in their primary sequence and attract attention because they have been shown to function efficiently in a broad range of organisms from E.coli to mice.