PT  - JOURNAL ARTICLE
AU  - Dheva Setiaputra
AU  - Cristina Escribano-Diaz
AU  - Julia K. Reinert
AU  - Pooja Sadana
AU  - Dali Zong
AU  - Elsa Callen
AU  - Jan Seebacher
AU  - Andre Nussenzweig
AU  - Nicolas H. Thomä
AU  - Daniel Durocher
TI  - RIF1 acts in DNA repair through phosphopeptide recognition of 53BP1
AID  - 10.1101/2021.04.26.441429
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.04.26.441429
4099  - http://biorxiv.org/content/early/2021/04/26/2021.04.26.441429.short
4100  - http://biorxiv.org/content/early/2021/04/26/2021.04.26.441429.full
AB  - The chromatin-binding protein 53BP1 promotes DNA repair by orchestrating the recruitment of downstream effectors including PTIP, RIF1 and shieldin to DNA double-strand break sites. While how PTIP recognizes 53BP1 is known, the molecular details of RIF1 recruitment to DNA damage sites remains undefined. Here, we report that RIF1 is a phosphopeptide-binding protein that directly interacts with three phosphorylated 53BP1 epitopes. The RIF1-binding sites on 53BP1 share an essential LxL motif followed by two closely apposed phosphorylated residues. Simultaneous mutation of these sites on 53BP1 abrogates RIF1 accumulation into ionizing radiation-induced foci, but surprisingly only fully compromises 53BP1-dependent DNA repair when an alternative mode of shieldin recruitment to DNA damage sites is also disabled. Intriguingly, this alternative mode of recruitment still depends on RIF1 but does not require its interaction with 53BP1. RIF1 therefore employs phosphopeptide recognition to promote DNA repair but also modifies shieldin action independently of 53BP1 binding.Competing Interest StatementDD is a shareholder of and advisor to Repare Therapeutics.