FIGURE 2.

Synthetic lethality of Pol δ^A699Q with exonuclease and mismatch repair deficiency. Haploid yeast cells that are positive or negative for the mismatch repair protein Msh2 are plated on 5-fluororotic acid plates to select for an expression plasmid containing either wild type Pol δ, Pol δ^A699Q, or exonuclease-deficient Pol δ^A699Q. Wild type Pol δ permits growth in both Msh2-containing and Msh2-deficient cells. Pol δ^A699Q, however, exhibits growth in Msh2-containing cells but not in the context of mismatch repair deficiency and also requires exonuclease activity for survival.