Fen-1 Facilitates Homologous Recombination by Removing Divergent Sequences at DNA Break Ends
- 1 August 2005
- journal article
- research article
- Published by Taylor & Francis in Molecular and Cellular Biology
- Vol. 25 (16), 6948-6955
- https://doi.org/10.1128/mcb.25.16.6948-6955.2005
Abstract
Homologous recombination (HR) requires nuclease activities at multiple steps, but the contribution of individual nucleases to the processing of double-strand DNA ends at different stages of HR has not been clearly defined. We used chicken DT40 cells to investigate the role of flap endonuclease 1 (Fen-1) in HR. FEN-1-deficient cells exhibited a significant decrease in the efficiency of immunoglobulin gene conversion while being proficient in recombination between sister chromatids, suggesting that Fen-1 may play a role in HR between sequences of considerable divergence. To clarify whether sequence divergence at DNA ends is truly the reason for the observed HR defect in FEN-1−/− cells we inserted a unique I-SceI restriction site in the genome and tested various donor and recipient HR substrates. We found that the efficiency of HR-mediated DNA repair was indeed greatly diminished when divergent sequences were present at the DNA break site. We conclude that Fen-1 eliminates heterologous sequences at DNA damage site and facilitates DNA repair by HR.Keywords
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