Exchangeability of mammalian DNA ligases between base excision repair pathways.
In mammalian cells, DNA ligase IIIalpha and DNA ligase I participate in the short- and long-patch base excision repair pathways, respectively. Using an in vitro repair assay employing DNA ligase-depleted cell extracts and DNA substrates containing a single lesion repaired either through short-patch (regular abasic site) or long-patch (reduced abasic site) base excision repair pathways, we addressed the question whether DNA ligases are specific to each pathway or if they are exchangeable. We find that immunodepletion of DNA ligase I did not affect the short-patch repair pathway but blocked long-patch repair, suggesting that DNA ligase IIIalpha is not able to substitute DNA ligase I during long-patch repair. In contrast, immunodepletion of DNA ligase IIIalpha did not significantly affect either pathway. Moreover, repair of normal abasic sites in wild-type and X-ray cross-complementing gene 1 (XRCC1)-DNA ligase IIIalpha-immunodepleted cell extracts involved similar proportions of short- and long-patch repair events. This suggests that DNA ligase I was able to efficiently substitute the XRCC1-DNA ligase IIIalpha complex during short-patch repair.
Radiation and Genome Stability Unit, Medical Research Council, Harwell, Oxfordshire OX11 0RD, United Kingdom.
Kate M
KM
Sleeth
Robert L
RL
Robson
Grigory L
GL
Dianov
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000172:deficiency / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D000075223:Poly-ADP-Ribose Binding Proteins; D013997:Time Factors; D000076105:X-ray Repair Cross Complementing Protein 1; D029867:Xenopus Proteins
D004268:DNA-Binding Proteins; C000607892:LIG1 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; D029867:Xenopus Proteins; D004247:DNA; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus