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Double-strand DNA Break Formation Mediated by Flap Endonuclease-1.
- Source :
-
Journal of Biological Chemistry . 9/12/2003, Vol. 278 Issue 37, p35279-35285. 7p. 4 Diagrams, 13 Graphs. - Publication Year :
- 2003
-
Abstract
- Double-strand DNA breaks are the most lethal type of DNA damage induced by ionizing radiations. Previously, we reported that double-strand DNA breaks can be enzymatically produced from two DNA damages located on opposite DNA strands 18 or 30 base pairs apart in a cell-free double-strand DNA break formation assay (Vispé, S., and Satoh, M. S. (2000) J. Biol. Chem. 275, 27386-27392). In the assay that we developed, these two DNA damages are converted into single-strand interruptions by enzymes involved in base excision repair. We showed that these single-strand interruptions are convetted into double-strand DNA breaks; however, it was not due to spontaneous denaturation of DNA. Thus, we proposed a model in which DNA polymerase δ/∈, by producing repair patches at single-strand interruptions, collide, resulting in double-strand DNA break formation. We tested the model and investigated whether other enzymes/factors are involved in double-strand DNA break formation. Here we report that, instead of DNA polymerase δ/∈, flap endonuclease-1 (FEN-l), an enzyme involved in base excision repair, is responsible for the formation of double-strand DNA break in the assay. Furthermore, by transfecting a flap endonuclease-1 expression construct into cells, thus altering their flap endonuclease-1 content, we found an increased number of double-strand DNA breaks after γ-ray irradiation of these cells. These results suggest that flap endonuclease-1 acts as a double-strand DNA break formation factor. Because FEN-1 is an essential enzyme that plays its roles in DNA repair and DNA replication, DSBs may be produced in cells as by-products of the activity of FEN-1. [ABSTRACT FROM AUTHOR]
- Subjects :
- *IONIZING radiation
*DNA damage
*DNA polymerases
Subjects
Details
- Language :
- English
- ISSN :
- 00219258
- Volume :
- 278
- Issue :
- 37
- Database :
- Academic Search Index
- Journal :
- Journal of Biological Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 10995813