A DNA double strand break (DSB) is one of the most cytotoxic DNA lesions, but it can be repaired by non-homologous end joining (NHEJ) or by homologous recombination. The choice between these two repair pathways depends on the cell cycle stage. Although NHEJ constitutes a simple re-ligation reaction, the regulatory mechanism(s) controlling its activity has not been fully characterized. LIF1 is a regulatory subunit of the NHEJ-specific DNA ligase IV and interacts with XRS2 of the MRX complex which is a key factor in DSB repair. Specifically, the C-terminal region of LIF1, which contains a CK2-specific phosphorylation motif, interacts with the FHA domain of XRS2 during canonical- NHEJ (C-NHEJ). Herein, we show that LIF1 and CKA2, a catalytic subunit of yeast CK2, interact and that the C-terminal phosphorylation consensus motif in LIF1 is phosphorylated by recombinant CK2. These observations suggest that phosphorylation of LIF1 by CK2 at a DSB site promotes the LIF1-XRS2 interaction and facilitates C-NHEJ.

• PMID: 29778533
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Journal Article | Research Support, Non-U.S. Gov't

Authors

Matsuzaki K, Shinohara M

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