Site-specific recombination in Schizosaccharomyces pombe and systematic assembly of a 400kb transgene array in mammalian cells using the integrase of Streptomyces phage phi BT1

We have established the integrase of the Streptomyces phage phi BT1 as a tool for eukaryotic genome manipulation. We show that the phi BT1 integrase promotes efficient reciprocal and conservative site-specific recombination in vertebrate cells and in Schizosaccharomyces pombe, thus establishing the utility of this protein for genome manipulation in a wide range of eukaryotes. We show that the phi BT1 integrase can be used in conjunction with Cre recombinase to promote the iterative integration of transgenic DNA. We describe five cycles of iterative integration of a candidate mouse centromeric sequence 80 kb in length into a human mini-chromosome within a human-Chinese hamster hybrid cell line. These results establish the generality of the iterative site-specific integration technique.