Intrachromosomal Recombination in Yeast

Spontaneous and induced mitotic recombinations are driven by lesions such as single-strand nicks and gaps and double-strand breaks in the genome. For regions of the genome that are not repetitive, spontaneous recombination rates are too low to be detected by simple screening and require reporters where a recombination product can be selected. This chapter describes commonly used types of reporters where a gene is duplicated as direct repeats and both copies are mutated with different mutations, rendering the cell defective for the gene and auxotrophic for the gene product. Recombination between the two defective copies can result in a wild-type gene and a prototrophic phenotype for the cell. Methods to use these types of reporters to determine recombination rates between the two gene copies are described, and their use in monitoring both increased and decreased recombinations is discussed.