Abstract
The XPF-ERCC1 heterodimer is a structure-specific endonuclease that is essential for nucleotide excision repair (NER) and interstrand crosslink (ICL) repair in mammalian cells. However, whether and how XPF binding to ERCC1 is regulated has not yet been established. Here, we show that TIP60, also known as KAT5, a haplo-insufficient tumor suppressor, directly acetylates XPF at Lys911 following UV irradiation or treatment with mitomycin C and that this acetylation is required for XPF-ERCC1 complex assembly and subsequent activation. Mechanistically, acetylation of XPF at Lys911 disrupts the Glu907-Lys911 salt bridge, thereby leading to exposure of a previously unidentified second binding site for ERCC1. Accordingly, loss of XPF acetylation impairs the damage-induced XPF-ERCC1 interaction, resulting in defects in both NER and ICL repair. Our results not only reveal a mechanism that regulates XPF-ERCC1 complex assembly and activation, but also provide important insight into the role of TIP60 in the maintenance of genome stability.
Highlights
The XPF-ERCC1 heterodimer is a structure-specific endonuclease that is essential for nucleotide excision repair (NER) and interstrand crosslink (ICL) repair in mammalian cells
To investigate how TIP60 contributes to the tolerance/repair of UV damage, we first examined whether depletion of TIP60 affected UV-induced proliferating cell nuclear antigen (PCNA) mono-ubiquitylation, a central event in the Translesion DNA synthesis (TLS) pathway[38]
Downregulation of TIP60 did not affect UV-induced polymerase eta (Polη) foci formation (Supplementary Fig. 1C, D). These findings suggest that TIP60 is not required for TLS and may play a role in the NER pathway
Summary
The XPF-ERCC1 heterodimer is a structure-specific endonuclease that is essential for nucleotide excision repair (NER) and interstrand crosslink (ICL) repair in mammalian cells. Loss of XPF acetylation impairs the damage-induced XPF-ERCC1 interaction, resulting in defects in both NER and ICL repair. Our results reveal a mechanism that regulates XPF-ERCC1 complex assembly and activation, and provide important insight into the role of TIP60 in the maintenance of genome stability. TIP60 is an acetyltransferase involved in the regulation of a wide variety of cellular activities, including gene transcription, chromatin remodeling, and DNA damage repair[27,28,29]. Downregulation of TIP60 did not affect FANCD2 mono-ubiquitination or its localization to DNA damage sites following treatment with mitomycin C (MMC)[35], indicating that TIP60 may facilitate ICL repair by a yet-unknown mechanism. The damage-induced XPF-ERCC1 interaction requires TIP60dependent acetylation of XPF at Lys[911], which disrupts the Glu907-Lys[911] salt bridge, thereby exposing a previously unidentified second binding site for ERCC1. Our results provide mechanistic insight into the role of TIP60 in the maintenance of genome stability
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