Involvement of flap endonuclease 1 in base excision DNA repair.
Base excision repair can proceed in either one of two alternative pathways: a DNA polymerase beta-dependent pathway and a proliferating cell nuclear antigen (PCNA)-dependent pathway. Excision of an apurinic/apyrimidinic (AP) site by cutting the phosphate backbone on its 3' side following incision at its 5' side by AP endonuclease is a prerequisite to completion of these repair pathways. Using a reconstituted system with the proteins derived from Xenopus laevis, we found that flap endonuclease 1 (FEN1) was a factor responsible for the excision of a 5'-incised AP site in the PCNA-dependent pathway. In this pathway, DNA synthesis was not required for the action of FEN1 in the presence of PCNA and a replication factor C-containing fraction. The polymerase beta-dependent pathway could also use FEN1 for excision of the synthetic AP sites, which were not susceptible to beta-elimination. In this pathway, FEN1 was functional without PCNA and replication factor C but required the DNA synthesis, which led to a flap structure formation.
Kim
K
K
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Biade
S
S
Matsumoto
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004260:DNA Repair; D004261:DNA Replication; D004706:Endodeoxyribonucleases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D045585:Flap Endonucleases; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014982:Xenopus laevis
D009838:Oligodeoxyribonucleotides; D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins; D004706:Endodeoxyribonucleases; D045585:Flap Endonucleases; C468317:FEN1 protein, human