FIG. 5.

G44S mutant mitotic phenotypes are suppressed by overexpressing Sgo1p. (A) Sgo1p overproduction specifically rescues the mitotic phenotypes of G44S mutant cells. The SGO1 ORF was cloned into a 2μm plasmid bearing the promoter and terminator sequences of ADH1. WT and G44S mutant cells transformed with SGO1 or the corresponding vector were tested under the indicated conditions. (B) Left panel, cell viability test after benomyl treatment. This plot was generated from three independent experiments, and the error bars depict the standard deviations. Right panel, chromosome missegregation assay. Shown are percentages of two-GFP-dotted G₁-phase cells. Data were collected from three or four independent cultures, and error bars represent standard deviations. See the legend to Fig. 2B and C for details. (C) Tension-sensing defects conferred by the G44S mutation are alleviated by SGO1 overexpression. G44S mutant cells receiving a 2μm plasmid with or without the ADH1-driven SGO1 gene were tested for the molecular response following MCD1 shutdown. Experiments were done exactly as those shown in Fig. 4. (D) Neither SGO1 transcription nor protein abundance is affected by the G44S mutation. Left, reverse transcription (RT)-PCR shows normal expression of SGO1 in the WT and G44S mutant strains. Right, Western blotting of C′-6×HA-tagged Sgo1p demonstrates the equal abundance of Sgo1p in these two strains. The loading control is a cross-reacting band from both yeast lysates.