Figure 4.—

Model of gap repair involving two-end invasion and lagging-strand synthesis. (A) A double-strand break is generated by I-SceI, followed by the processing of DNA ends, strand invasion, and DNA synthesis. Whether or not the branches migrate following DNA synthesis has not been addressed in this study. Ligation of the ends may occur by either homologous end joining (B) or nonhomologous end joining (NHEJ) after resection of the single-stranded ends (C). The model in B is a modification of the SDSA model proposed by Nassif et al. (1994). An alternative model involving Holliday junction formation and resolution without associated crossing over is also compatible with our data.