title: FEN1 participates in repair of the 5'-phosphotyrosyl terminus of DNA single-strand breaks.
abstract: Etoposide is a widely used anticancer drug and a DNA topoisomerase II (Top2) inhibitor. Etoposide produces Top2-attached single-strand breaks (Top2-SSB complex) and double-strand breaks (Top2-DSB complex) that are thought to induce cell death in tumor cells. The Top2-SSB complex is more abundant than the Top2-DSB complex. Human tyrosyl-DNA phosphodiesterase 2 (TDP2) is required for efficient repair of Top2-DSB complexes. However, the identities of the proteins involved in the repair of Top2-SSB complexes are unknown, although yeast genetic data indicate that 5' to 3' structure-specific DNA endonuclease activity is required for alternative repair of Top2 DNA damage. In this study, we purified a flap endonuclease 1 (FEN1) and xeroderma pigmentosum group G protein (XPG) in the 5' to 3' structure-specific DNA endonuclease family and synthesized single-strand break DNA substrates containing a 5'-phoshotyrosyl bond, mimicking the Top2-SSB complex. We found that FEN1 and XPG did not remove the 5'-phoshotyrosyl bond-containing DSB substrates but removed the 5'-phoshotyrosyl bond-containing SSB substrates. Under DNA repair conditions, FEN1 efficiently repaired the 5'-phoshotyrosyl bond-containing SSB substrates in the presence of DNA ligase and DNA polymerase. Therefore, FEN1 may play an important role in the repair of Top2-SSB complexes in etoposide-treated cells.
authors.affiliation: Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kametani
authors.affiliation: Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Takahata
authors.affiliation: Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Narita
authors.affiliation: Laboratories for Organismal Biosystems, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Kiyoji
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Iwai
authors.affiliation: Graduate School of Engineering Science, Osaka University Graduate School of Engineering Science, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan and Kuraoka@chem.es.osaka-u.ac.jp.
authors.forename: Isao
authors.initials: I
authors.lastname: Kuraoka
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D053904:DNA Breaks, Single-Stranded; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism; D004257:DNA Polymerase II / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology*; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases; D000075223:Poly-ADP-Ribose Binding Proteins; D011994:Recombinant Proteins / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism / Q000494:pharmacology; D000099250:DNA Excision Repair Protein ERCC-5
chemical_list: D000951:Antigens, Neoplasm; D000072481:DNA Ligase ATP; D011088:DNA Ligases; D004257:DNA Polymerase II; D004250:DNA Topoisomerases, Type II; D004268:DNA-Binding Proteins; D004720:Endonucleases; D005047:Etoposide; D045585:Flap Endonucleases; D009687:Nuclear Proteins; D010727:Phosphoric Diester Hydrolases; D000075223:Poly-ADP-Ribose Binding Proteins; D011994:Recombinant Proteins; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; D000099250:DNA Excision Repair Protein ERCC-5; C468317:FEN1 protein, human; C474866:TDP2 protein, human; C000618811:TOP2A protein, human