Daxx Interacts With Phage ΦBT1 Integrase and Inhibits Its Recombination

The bacterial phage Phi BT1 integrase is a promising tool due to its site-specific transgene character. It enriches the site-specific transgenic tools and provides the possibility for multiple site-specific transgenic manipulations. To improve its safety as a vector of gene therapy, it is necessary to investigate the potential interactions between Phi BT1 and proteins in mammalian host cells. Yeast mating and co-immunoprecipitation assay indicated that a tetrapeptide 433RFAL436 in Phi BT1 integrase was responsible for Phi BT1 and Daxx interaction. It was also demonstrated that over-expression of Daxx could reduce Phi BT1 mediated recombination rate in 293T cells by using Phi BT1 report system. It is the first time to identify a cellular protein interacting with Phi BT1 integase and inhibiting its recombination efficiency. This result might be useful for improving the Phi BT1 integrase mediated transgene methods and directing the selection of target cells for Phi BT1 integrase.