Abstract
Double-strand breaks (DSBs) threaten the integrity of chromosomes. Consequently, cells have devised a number of mechanisms to repair broken chromosomes. There are several competing mechanisms of homologous recombination as well as multiple nonhomologous end-joining pathways that can repair chromosome breaks with varying degrees of fidelity. This review summarizes what has been learned about DSB repair in the budding yeast, Saccharomyces cerevisiae, where it is possible to create, rapidly and synchronously, a specific DSB using inducible meganucleases, HO or I-SceI. The physical monitoring of DNA undergoing recombination and the binding of various recombination proteins in the vicinity of the DSB provides a picture of the sequence of molecular events during recombination. We first examine an intrachromosomal recombination event, MAT gene switching, and then to interchromosomal ectopic events. In addition, repair by single-stand annealing, break-induced replication and nonhomologous end-joining are discussed.