Study of a telomere complex protection against chromosome fusions

Telomeres are nucleoprotein structures capping chromosomes extremities which they prevent native chromosome ends from being recognized and processed as double-stranded break ends by DNA damage repair pathways. Paradoxically, Ku protein binds telomere DNA ends and contributes to their protection. But Ku is also an essential actor of the NHEJ double strand break repair pathway and it can facilitate NHEJ-dependent fusions between telomeres. Our aim is to unravel the molecular mechanisms played by telomere factors Rap1, Rif2 and Sir4 to protect telomeres against the action of the DNA repair factor Ku. We have obtained a first structure of scKu-DNA-scRap1 complex using a glacios of Institut Pasteur and Cryosparc reconstruction, but to improve the resolution we have prepared new grids after purification of complex on a gel filtration column and we would like use the Titan Krios of ERSF to collect a new serial images.