FIG. 1.

(A) Three alternative models of DSB-initiated recombination resulting in gene conversion. (Panel 1) DSBR model. The DSBR model involves invasion of a homologous template by the two broken ends and formation of an intermediate containing two Holliday junctions. After mismatch repair, resolution leads to gene conversion. (Panel 2) One-ended SDSA model. A single broken end invades the homologous sequence and primes DNA synthesis. Newly synthesized DNA reanneals and ligates to the opposite broken arm. A second round of mismatch repair results in gene conversion. (Panel 3) Double-ended SDSA model (DE-SDSA). Invasion is carried out by the two broken arms, followed by DNA synthesis and annealing of the two newly synthesized DNA. Only one round of hDNA repair is necessary for gene conversion. B and R represent the BamHI and EcoRI restriction site polymorphisms, respectively. (B) Schematic representation of our experimental system. Open rectangles represent the ura3 alleles on chromosomes II and V. A black box represents the HOcs; a gray box depicts the inactive HOcs-inc flanked by the BamHI (B) and EcoRI (R) restriction sites. Transfer of the cells to galactose-containing medium results in gene conversion.