Large inverted repeats in the vicinity of a single double-strand break strongly affect repair in yeast diploids lacking Rad51

DNA double-strand breaks (DSBs) are critical lesions that can lead to cell death or chromosomal rearrangements. Rad51 is necessary for most mitotic and meiotic DSB repair events, although a number of RAD51-independent pathways exist. Previously, we described DSB repair in rad51 Delta yeast diploids that was stimulated by a DNA region termed "facilitator of break-induced replication" (FBI) located approximately 30 kb from the site of an HO-induced DSB. Here, we demonstrate that FBI is a large inverted DNA repeat that channels the repair of DSBs into the single-strand annealing-gross chromosomal rearrangements (SSA-GCR) pathway. Further, analysis of DSB repair in rad54 Delta cells allowed us to propose that the SSA-GCR repair pathway is suppressed in the presence of Rad51p. Therefore, an additional role of Rad51 might be to protect eukaryotic genomes from instabilities by preventing chromosomal rearrangements. (C) 2008 Elsevier B.V. All rights reserved.