Involvement of XRCC1 and DNA ligase III gene products in DNA base excision repair.
DNA ligase III and the essential protein XRCC1 are present at greatly reduced levels in the xrcc1 mutant CHO cell line EM-C11. Cell-free extracts prepared from these cells were used to examine the role of the XRCC1 gene product in DNA base excision repair in vitro. EM-C11 cell extract was partially defective in ligation of base excision repair patches, in comparison to wild type CHO-9 extracts. Of the two branches of the base excision repair pathway, only the single nucleotide insertion pathway was affected; no ligation defect was observed in the proliferating cell nuclear antigen-dependent pathway. Full complementation of the ligation defect in EM-C11 extracts was achieved by addition to the repair reaction of recombinant human DNA ligase III but not by XRCC1. This is consistent with the notion that XRCC1 acts as an important stabilizing factor of DNA ligase III. These data demonstrate for the first time that xrcc1 mutant cells are partially defective in ligation of base excision repair patches and that the defect is specific to the polymerase beta-dependent single nucleotide insertion pathway.
Cappelli
E
E
DNA Repair Unit, C.S.T.A. Laboratory-Istituto Nazionale Ricerca Cancro, L.go Rosanna Benzi n. 10, 16132 Genova, Italy.
Taylor
R
R
Cevasco
M
M
Abbondandolo
A
A
Caldecott
K
K
Frosina
G
G
D000818:Animals; D016466:CHO Cells; D002474:Cell-Free System; D006224:Cricetinae; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism*; D004256:DNA Polymerase I / Q000378:metabolism; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D006801:Humans; D000075223:Poly-ADP-Ribose Binding Proteins; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D000076105:X-ray Repair Cross Complementing Protein 1; D029867:Xenopus Proteins
D004268:DNA-Binding Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; D029867:Xenopus Proteins; D004256:DNA Polymerase I; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus; C000618817:LIG3 protein, human