Figure 1.

HO endonuclease induction of DSB repair events in Mush18/21. (A) The substrate consists of inverted repeats comprised of two truncated but overlapping alleles of TRP1, a full-length CAN gene, and a truncated can1-5′Δ allele, separated by a full-length HIS3 gene. The extent of the inverted repeat sequence is marked by the gray double-headed arrow. Between the trp1-3′Δ allele and the full-length CAN1 gene, there is a unique recognition sequence for the HO endonuclease. The normal HO recognition sequence at the MAT locus has been mutated (MATα-inc). The substrate is inserted near the MATα locus on chromosome III. (B) Structure of the palindromic duplications. Note that the can1-5′Δ, HIS3, and a variable amount of the 3′ end of the CAN1 gene have been duplicated. The increase in the extent of the inverted repeat is indicated by the gray double-headed arrow.