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

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 use Xenopus laevis egg extract to investigate the role of the intrinsically disordered C-terminal tail of the XRCC4-like factor (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. Although 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.

SUBMITTER: Carney SM

PROVIDER: S-EPMC7744095 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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

Carney Sean M SM Moreno Andrew T AT Piatt Sadie C SC Cisneros-Aguirre Metztli M Lopezcolorado Felicia Wednesday FW Stark Jeremy M JM Loparo Joseph J JJ

eLife 20201208

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 use <i>Xenopus laevis</i> egg extract to investigate the role of the intrinsically disordered C-terminal tail of the XRCC4-like factor (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 ...[more]

PMID: 33289484

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