Meta-Biol

• Pathways

Two DNA helicases XPB (ERCC3) and XPD (ERCC2), which are part of the TFIIH complex, unwind the distorted DNA duplex around the lesion to form an open bubble structure that exposes the damaged site. The helicase activity of the TFIIH complex is stimulated by the presence of XPA and the XPC:RAD23:CETN2 complex (Winkler et al. 2001). The 5'->3' directed helicase activity of ERCC2 (Kuper et al. 2012) is crucial for unwinding of the distorted dsDNA during nucleotide excision repair (NER) (Coin et al. 2007). The 3'->5' directed DNA helicase ERCC3 contributes to dsDNA unwinding during NER through ATP hydrolysis (Coin et al. 2007). In addition to DNA unwinding, ERCC2 and ERCC3 verify the presence of DNA damage (Oksenych et al. 2009, Mathieu et al. 2010, Mathieu et al. 2013). Verification of DNA damage also involves XPA (Camenisch et al. 2006). The binding site of XPC determines which DNA strand is selected by ERCC2 to verify the presence of lesions (Sugasawa et al. 2009).