Structural study of gene rearrangement mechanisms driven by Paramecium transposases in tight collaboration with c-NHEJ

Although considered as the most toxic DNA lesion, programmed DSBs (prDSBs) are essential for a number of physiological processes such as T and B cell development, meiosis, transcription and replication. prDSBs require tight coordination between DNA cleavage and DSB repair. To unravel this close collaboration we use the ciliate Paramecium tetraurelia. Indeed, during its new polyploidy macronucleus (MAC) development, the Piggy-Mac transposase and its partners, PiggyMac-Like (PgmL1 to PgmL5) excise DNA at specific DNA sequence. The prDSBs generated are then repaired by the Non-Homologous End Joining Pathway. Our collaborators have recently shown that the PgmL1 and PgmL3 are the first factors to step in the recognition of the specific DNA sequences. Thus, the major aim of this proposal is to characterize the structural functions of PgmL1 and PgmL3 in presence or not of DNA molecule by cryoEM.