Figure 1.
The diagram is divided into two main parts: canonical NER and impaired NER. In canonical NER, the process involves several steps: ERCC1-XPF incision, XPG incision, and repair synthesis plus ligation. The diagram shows the proteins and enzymes involved, including ERCC1, XPF, XPA, RPA, TFIIH, XPG, PCNA, DNA polymerase, and ligase. These components work together to recognize and repair DNA lesions. In impaired NER, the process differs as there is no XPG incision, leading to the recruitment of EXO1, which resects the lesion-containing strand. This results in the formation of single-strand DNA gaps, activation of the DNA damage response, and delayed repair synthesis and ligation. The diagram visually represents the interactions and sequence of events in both canonical and impaired NER pathways.
Canonical and impaired NER reactions. In normal NER, excision of the lesion-containing strand by the ERCC1-XPF and XPG exonucleases is coordinated with repair synthesis and ligation. If NER is impaired by inhibition of the 3′ incision by XPG, EXO1 can resect the lesion-containing strand, leading to the formation of ssDNA gaps, DNA damage response activation, and eventually delayed repair synthesis and ligation. EXO1, exonuclease 1.