1. Uncoupling programmed DNA cleavage and repair scrambles the Paramecium somatic genome.
- Author
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Bischerour J, Arnaiz O, Zangarelli C, Régnier V, Iehl F, Ropars V, Charbonnier JB, and Bétermier M
- Subjects
- DNA Breaks, Double-Stranded, Genome, Protozoan, Ku Autoantigen metabolism, Ku Autoantigen genetics, DNA Repair, Protozoan Proteins metabolism, Protozoan Proteins genetics, DNA End-Joining Repair, Paramecium genetics, Paramecium metabolism, DNA Cleavage
- Abstract
In the ciliate Paramecium, precise excision of numerous internal eliminated sequences (IESs) from the somatic genome is essential at each sexual cycle. DNA double-strands breaks (DSBs) introduced by the PiggyMac endonuclease are repaired in a highly concerted manner by the non-homologous end joining (NHEJ) pathway, illustrated by complete inhibition of DNA cleavage when Ku70/80 proteins are missing. We show that expression of a DNA-binding-deficient Ku70 mutant (Ku70-6E) permits DNA cleavage but leads to the accumulation of unrepaired DSBs. We uncoupled DNA cleavage and repair by co-expressing wild-type and mutant Ku70. High-throughput sequencing of the developing macronucleus genome in these conditions identifies the presence of extremities healed by de novo telomere addition and numerous translocations between IES-flanking sequences. Coupling the two steps of IES excision ensures that both extremities are held together throughout the process, suggesting that DSB repair proteins are essential for assembly of a synaptic precleavage complex., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
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