Tethering recombination initiation proteins in Saccharomyces cerevisiae promotes double strand break formation

Meiotic recombination in Saccharomyces cerevisiae is initiated by the creation of DNA double strand breaks (DSBs), an event requiring 10 recombination initiation proteins. Published data indicate that these 10 proteins form three main interaction subgroups [(Spo11-Rec102-Rec104-Ski8), (Rec114-Rec107-Mei4), and (Mre11-Rad50-Xrs2)], but certain components from each subgroup may also interact. Although several of the protein-protein interactions have been defined, the mechanism for DSB formation has been challenging to define. Using a variation of the approach pioneered by others, we have tethered 8 of the 10 initiation proteins to a recombination coldspot and discovered that in addition to Spo11, 6 others (Rec102, Rec104, Ski8, Rec114, Rec107, and Mei4) promote DSB formation at the coldspot, albeit with different frequencies. Of the 8 proteins tested, only Mre11 was unable to cause DSBs even though it binds to UAS(GAL) at GAL2. Our results suggest there may be several ways that the recombination initiation proteins can associate to form a functional initiation complex that can create DSBs.