Nern, A. et al. Proc. Nat. Acad. Sci. 108, 14198–14203 (2011).

Expanding the toolset for site-specific recombination would accommodate more complex genome manipulations. Starting with predictions of yeast recombinases similar to Flp recombinase, Nern et al. engineered three new genes for fruit fly codon usage and short half-life. They showed that modified recombinases KD, B2 and B3, along with the previously identified R recombinase exhibited high efficiency, low toxicity and no cross-talk in the fly, and that KD and B3 recombinases functioned in mammalian cells.