XRCC1 interactions with multiple DNA glycosylases: a model for its recruitment to base excision repair.
Repair of chemically modified bases in DNA is accomplished through base excision repair (BER). This pathway is initiated by a specific DNA glycosylase that recognizes and excises the altered base to yield an abasic (AP) site. After cleavage of the AP site by APE1, repair proceeds through re-synthesis and ligation steps. In mammalian cells, the XRCC1 protein, essential for the maintenance of genomic stability, is involved in both base excision and single-strand break repair. XRCC1 participates in the first step of BER by interacting with the human DNA glycosylases hOGG1 and NEIL1. To analyze the possibility of a general mechanism involving the interaction of XRCC1 with DNA glycosylases we used XRCC1 to pull-down DNA glycosylases activities from human cell extracts. XRCC1 co-purifies with DNA glycosylase activities capable of excising hypoxanthine and dihydrothymine, in addition to 8-oxoguanine, but not uracil. Biochemical analyses with the purified proteins confirmed the interactions between XRCC1 and MPG, hNTH1 or hNEIL2. Furthermore, XRCC1 stimulates the activities of these enzymes. In vivo localization studies show that after genotoxic treatments these DNA glycosylases can be found associated with XRCC1 foci. Our results support a BER model in which XRCC1 is recruited to the repair of alkylated or oxidized bases by the enzyme recognizing the lesion. XRCC1 would then coordinate the subsequent enzymatic steps and modulate the activities of all the proteins involved.
Campalans
Anna
A
Département de Radiobiologie et Radiopathologie, CEA, UMR217 CNRS/CEA, 18 Route du Panorama, F-92265 Fontenay aux Roses, France.
Marsin
Stéphanie
S
Nakabeppu
Yusaku
Y
O'connor
Timothy R
TR
Boiteux
Serge
S
Radicella
J Pablo
JP
D002467:Cell Nucleus / Q000737:chemistry; D045647:DNA Glycosylases / Q000032:analysis / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007042:Hypoxanthines / Q000378:metabolism; D025941:Protein Interaction Mapping; D000076105:X-ray Repair Cross Complementing Protein 1
D004268:DNA-Binding Proteins; D007042:Hypoxanthines; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; C024829:8-hydroxyguanine; D006147:Guanine; D045647:DNA Glycosylases; C473634:NEIL1 protein, human; C479058:oxoguanine glycosylase 1, human