Open AccessThe DNA helicases acting in nucleotide excision repair, XPD, CSB and XPB, are not required for PCNA‐dependent repair of abasic sites
Author(s) -
Cappelli Enrico,
Carrozzino Fabio,
Abbondandolo Angelo,
Frosina Guido
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00050.x
Subject(s) - nucleotide excision repair , base excision repair , proliferating cell nuclear antigen , dna repair , cockayne syndrome , biology , xeroderma pigmentosum , ap site , microbiology and biotechnology , dna damage , xrcc1 , biochemistry , dna , gene , genotype , single nucleotide polymorphism
DNA repair of abasic sites is accomplished in mammalian cells by two distinct base excision repair (BER) pathways: a single nucleotide insertion pathway and a proliferating cell nuclear antigen (PCNA)‐dependent pathway involving a resynthesis patch of 2–10 nucleotides 3′ to the lesion. The latter pathway shares some enzymatic components with the nucleotide excision repair (NER) pathway acting on damage induced by ultraviolet light: both pathways are strictly dependent on PCNA and several observations suggest that the polymerization and ligation phases may be carried out by common enzymatic activities (DNA polymerase δ/ε and DNA ligase I). Furthermore, it has been postulated that the transcription‐NER coupling factor Cockayne syndrome B has a role in BER. We have investigated whether three NER proteins endowed with DNA helicase activities (the xeroderma pigmentosum D and B gene products and the Cockayne syndrome B gene product) may also be involved in repair of natural abasic sites, by using the Chinese hamster ovary mutant cell lines UV5, UV61 and 27‐1. No defect of either the PCNA‐dependent or the single nucleotide insertion pathways could be observed in UV5, UV61 or 27‐1 mutant cell extracts, thus showing that the partial enzymatic overlap between PCNA‐dependent BER and NER does not extend to DNA helicase activities.