Recruitment and release of XPG during NER is controlled by pre- and post-incision factors and EXO1.

The XPG endonuclease is crucial for nucleotide excision repair (NER) and other genome maintenance pathways. Precise regulation of XPG recruitment and activity during DNA repair is essential to avoid erroneous DNA incisions and genomic instability. In this study, we employed live-cell imaging to investigate how XPG is regulated during NER, focusing on its dynamic interactions with key factors involved in the pre- and post-incision steps. We found that TFIIH and XPA facilitate recruitment and association of XPG with DNA damage and that XPG localizes separately from TFIIH to UV-induced lesions. Furthermore, our results show that XPG's dissociation from DNA damage is triggered by its own incision activity as well as by that of XPF. Additionally, the exonuclease EXO1 promotes XPG dissociation, likely by processing incised DNA, even in the absence of XPG-mediated incision. Our findings help to better understand the regulatory mechanisms that control XPG activity during NER and provide important insights into the complex dynamics of the repair process.