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bioRxiv · 10.1101/2020.07.29.227033

XLF acts as a flexible connector during non-homologous end joining

Carney, S. M.·Moreno, A. T.·Piatt, S. C.·Cisneros-Aguirre, M.·Lopezcolorado, F. W.·Stark, J. M.·Loparo, J. J.
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Abstract

Non-homologous end joining (NHEJ) is the predominant pathway that repairs DNA double strand breaks in vertebrates. During NHEJ DNA ends are held together by a multi-protein synaptic complex until they are ligated. Here we investigate the role of the intrinsically disordered C-terminal tail of XLF, a critical factor in end synapsis. We demonstrate that the XLF tail along with the Ku binding motif (KBM) at the extreme C-terminus are required for end joining. While the underlying sequence of the tail can be varied, a minimal tail length is required for NHEJ. Single-molecule FRET experiments that observe end synapsis in real-time show that this defect is due to a failure to closely align DNA ends. Our data supports a model in which a single C-terminal tail tethers XLF to Ku while allowing XLF to form interactions with XRCC4 that enable synaptic complex formation.

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Carney, S. M., Moreno, A. T., Piatt, S. C., Cisneros-Aguirre, M., Lopezcolorado, F. W., Stark, J. M., Loparo, J. J.. 2020-07-29. XLF acts as a flexible connector during non-homologous end joining. https://doi.org/10.1101/2020.07.29.227033

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