Figure 1. Plasmid shuffle for the functional analysis of essential yeast genes. The haploid knockout strain with a complementing wild‐type gene on the URA3 plasmid is transformed with a HIS3 plasmid with mutation in the gene of interest. Growth on 5‐FOA then selects for cells that have lost the URA3 plasmid, and the growth phenotype of the mutation is assessed.

Figure 2. Genetic interaction analysis by plasmid shuffle. Haploid double knockout strain with complementing double wild‐type gene URA3 plasmid is transformed with HIS3 and LEU2 plasmids with mutations in the genes of interest. Growth on 5‐FOA then selects for cells that have lost the URA3 plasmid, and the genetic interaction phenotype of the two mutations combined is assessed.

Figure 3. Example of the analysis. A 5‐FOA plate showing a typical synthetic genetic analysis of mutations in two essential yeast genes. The plate displays all the controls that should be included, and provides an example of a synthetic lethal interaction. (Plate supplied by Rebecca Hogg.)