Xeroderma pigmentosum complementation group C protein (XPC) serves as a general sensor of damaged DNA

Abstract

The xeroderma pigmentosum complementation group C protein (XPC) serves as the primary initiating factor in the global genome nucleotide excision repair pathway (GG-NER). Recent reports suggest XPC also stimulates repair of oxidative lesions by base excision repair. However, whether XPC distinguishes among various types of DNA lesions remains unclear. Although the DNA binding properties of XPC have been studied by several groups, there is a lack of consensus over whether XPC discriminates between DNA damaged by lesions associated with NER activity versus those that are not. In this study we report a high-throughput fluorescence anisotropy assay used to measure the DNA binding affinity of XPC for a panel of DNA substrates containing a range of chemical lesions in a common sequence. Our results demonstrate that while XPC displays a preference for binding damaged DNA, the identity of the lesion has little effect on the binding affinity of XPC. Moreover, XPC was equally capable of binding to DNA substrates containing lesions not repaired by GG-NER. Our results support an indirect read-out model for sensing the presence of lesions by human XPC and suggest XPC may act as a general sensor of damaged DNA capable of recognizing DNA containing lesions not repaired by NER.

Poly(ADP-ribose) polymerase 1 escorts XPC to UV-induced DNA lesions during nucleotide excision repair

“…For example, CPD are recognized and repaired even after DDB2 is degraded (12) or when the number of lesion sites exceeds the number of DDB2 molecules in the cell (13). In addition, XPC recognizes and starts NER at other types of DNA damages, such as bulky adducts and cross-links that are not likely to be recognized by DDB2, because these lesions cannot be accommodated in DDB2′s recognition pocket (14)(15)(16).…”

Ubiquitin-specific Protease 7 Regulates Nucleotide Excision Repair through Deubiquitinating XPC Protein and Preventing XPC Protein from Undergoing Ultraviolet Light-induced and VCP/p97 Protein-regulated Proteolysis

“…Interestingly, the XPC complex appears to recognize lesion-containing secondary DNA structures rather than lesions themselves (7). The nature of the lesion has little effect on the binding affinity of the XPC complex (8). For instance, the XPC complex is equally capable of binding to DNA substrates that are not repaired in vivo by NER, suggesting that XPC may be a general sensor of DNA lesions.…”

XPC: Going where no DNA damage sensor has gone before

“…Studies have shown that XPC preferentially binds to damaged DNA, yet the type of the lesion does not affect binding efficiencies [12, 13]. Furthermore, these studies demonstrated that XPC binds to lesions that are not even repaired by GG-NER [13].…”

“…Furthermore, these studies demonstrated that XPC binds to lesions that are not even repaired by GG-NER [13]. Appropriately considering XPC and Rad4 share most homology at their DNA binding domains, these two damage sensors bind DNA in the same topological manner [9, 14].…”

“…A more high-throughput approach, measuring binding affinities of XPC-Rad23 across a variety of chemically unrelated lesions, produced similar results. The authors concluded that XPC could serve as a general sensor of DNA damage [13]. Moreover, both groups suggested that the binding of XPC to a lesion, the first step of the bipartite damage recognition mechanism for processing DNA lesions (lesion recognition by XPC-Rad23 occurs first, followed by lesion verification by XPD in TFIIH [20, 52]), does not necessarily confirm that the lesion will be repaired by NER.…”