Dre recombinase, like Cre, is a highly efficient site-specific recombinase in E. coli, mammalian cells and mice

Key findings

Dre recombinase cloned from bacteriophage D6 achieved complete recombination between rox sites in E. coli under arabinose-inducible BAD promoter control with no background activity when uninduced. The temperature-sensitive pSC101 expression system provided excellent on-off regulation that was previously unachievable with Cre constructs. Orthogonality tests confirmed Dre produced no recombination between loxP sites and Cre produced no recombination between rox sites, validating independence from the Cre-loxP system.

The researchers generated CAGGs-Dre-IRES-puro constructs and established single-copy integration ES cell lines with germline transmission after 8-cell embryo injection. Rosa26-rox reporter ES cells and accompanying reporter mouse lines were created by gene targeting, providing standardized tools for Dre-mediated recombination. A CAGGs-Dre deleter mouse line was established for ubiquitous expression, and Dre-progesterone receptor fusion demonstrated ligand-responsive induction similar to Cre-ER systems.

In vivo experiments with Rosa26-rox reporter mice crossed to CAGGs-Dre deleter mice confirmed Dre recombinase functions with Cre-like efficiency in mammalian genome engineering applications. No crossover recombination occurred between Cre-rox or Dre-loxP combinations, establishing Dre as a fully orthogonal third recombinase system alongside Cre-loxP and Flp-FRT for sophisticated combinatorial site-specific recombination strategies in mice.