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Repair of clustered abasic DNA damages
Author(s) -
Paap Brigitte Katrin,
Sutherland Betsy M
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb34-c
Subject(s) - ap site , dna , dna damage , dna (apurinic or apyrimidinic site) lyase , chemistry , dna repair , enzyme , biophysics , microbiology and biotechnology , biochemistry , biology
Abasic clusters‐‐two or more abasic sites on opposing strands within one helical turn‐‐are induced in DNA by ionizing radiation. AP sites are recognized by AP endonucleases, which incise the DNA at the modified site and initiate further repair. Previous studies show the action of these enzymes on one or two lesions. But clusters generated by ionizing radiation may contain three or more lesions. How lesions in complex clusters are processed is not known. We used fluorescently‐labeled oligonucleotides to follow the fate of each DNA strand in a single reaction. Substrates were 51‐mer DNA duplexes with one uracil in one strand and one or two uracils on the other. The uracils were converted into abasic sites by UDG enzyme. The spaces between the abasic sites are of different lengths and in varying polarity. We analyzed how spacing and orientation of the abasic sites to each other affects incision by purified human APE1. Heavy charged particles found in space are suspected to cause complex clusters. With increased complexity of the DNA cluster damages, their toxicity is assumed to increase. We show, that it rather seems to be the constellation of the lesions that affects the repairability of the DNA damage, and with this the fate of the damaged cell.