251. TRF2-Mediated Control of Telomere DNA Topology as a Mechanism for Chromosome-End Protection.
- Author
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Benarroch-Popivker D, Pisano S, Mendez-Bermudez A, Lototska L, Kaur P, Bauwens S, Djerbi N, Latrick CM, Fraisier V, Pei B, Gay A, Jaune E, Foucher K, Cherfils-Vicini J, Aeby E, Miron S, Londoño-Vallejo A, Ye J, Le Du MH, Wang H, Gilson E, and Giraud-Panis MJ
- Subjects
- Ataxia Telangiectasia Mutated Proteins metabolism, Base Pairing, DNA metabolism, DNA Damage, DNA End-Joining Repair, HeLa Cells, Humans, Lysine metabolism, Models, Molecular, Mutation, Protein Structure, Tertiary, Shelterin Complex, Signal Transduction, Telomere-Binding Proteins metabolism, Telomeric Repeat Binding Protein 2 chemistry, DNA chemistry, Nucleic Acid Conformation, Telomere metabolism, Telomeric Repeat Binding Protein 2 metabolism
- Abstract
The shelterin proteins protect telomeres against activation of the DNA damage checkpoints and recombinational repair. We show here that a dimer of the shelterin subunit TRF2 wraps ∼ 90 bp of DNA through several lysine and arginine residues localized around its homodimerization domain. The expression of a wrapping-deficient TRF2 mutant, named Top-less, alters telomeric DNA topology, decreases the number of terminal loops (t-loops), and triggers the ATM checkpoint, while still protecting telomeres against non-homologous end joining (NHEJ). In Top-less cells, the protection against NHEJ is alleviated if the expression of the TRF2-interacting protein RAP1 is reduced. We conclude that a distinctive topological state of telomeric DNA, controlled by the TRF2-dependent DNA wrapping and linked to t-loop formation, inhibits both ATM activation and NHEJ. The presence of RAP1 at telomeres appears as a backup mechanism to prevent NHEJ when topology-mediated telomere protection is impaired., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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