Figure 3.

Sequence context and heteroduplex structure at the deletion. (A) Wild-type sequence. Lettering correspond to near-MfeI sites. Boxed base pairs are the two positions further mutagenized to generate MfeI sites. (B) Sequence of HetI or HetII at the deletion. Lettering indicates the MfeI spliced site. Boxed base pairs are the mutagenized positions. The 5 homologous bases beyond the change at 2401 and the 2 homologous bases beyond the change at 2872 are underlined. (C–F) Heteroduplex structures that may occur when a donor strand from HetI or HetII integrates into a wild-type chromosome and is blocked at the deletion. Only exchanges on the left side are represented. They are characterized as long bands carrying either AflII or ClaI sites (5′ and 3′, respectively, with HetI as donor; 3′ and 5′, respectively, with HetII as donor). Thick line, donor deleted strand; thin line, wild-type recipient. (C and E) Donor strand pairs until the 5 homologous bases beyond the MfeI substitution. (D and F) Donor strand is excluded at the MfeI change in spite of the 5 homologous bases.