Figure 4.

The Rrp44-exo mutation, but not the Rrp44-endo mutation, is synthetically lethal with loss of Xrn1. (A) In vivo analysis of Gal::rrp44 strains expressing WT-Rrp44 or Rrp44-exo in the absence of the cytoplasmic 5′–3′ exonuclease Xrn1. Strains were streaked for single colonies on selective plates containing either 2% galactose or 2% glucose and incubated at 30°C. (B) In vivo analysis of rrp44Δ strains expressing WT or mutant Rrp44 in the absence of Xrn1. Strains were streaked for single colonies on selective plates with or without 5-FOA, which selects for loss of the plasmid carrying URA3 and WT-RRP44, and incubated at 25°C.