In numerous eukaryotes, developmentally programmed elimination of germline DNA drives the plasticity of the somatic genome. Because of its unique nuclear dimorphism, Paramecium provides an extraordinary unicellular model to study the impact of transposable elements (TEs) on genome dynamics.
A major research line of our team aims at understanding the molecular mechanisms involved in programmed DNA elimination and its epigenetic control. We identified several key actors of IES excision. The PiggyMac endonuclease, a catalytically active domesticated PiggyBac transposase, introduces programmed DNA double-strand breaks (DSB) at IES ends and initiates their precise excision. PiggyMac works in association with five different domesticated transposases from the same family. We use molecular, biochemical and cellular approaches combined with reverse genetics and high-throughput next-generation sequencing to characterize the endonuclease-associated complex, the function of its different subunits and the way it recognizes its chromatin targets.