FIG. 1.

The histone H3 K4,36,79R mutant strain is inviable. (A) The growth phenotypes of double and triple mutants in histone H3 methylated lysine residues were examined. Fivefold serial dilutions of each yeast strain (from about 10⁴ cells) were spotted on SC-ADE medium or SC-ADE with 5-FOA as indicated. A wild-type (wt) histone H3 allele was present in each strain on SC-ADE plates but was lost from SC-ADE plates with 5-FOA. (B) Growth rates of histone mutant strains. The cell density of strains containing the H3 K4,36,79R, H3 Δ4-45, H3Δ, or wild-type alleles of histone H3 was monitored by measuring the optical density at different time points following the depletion of wild-type histone H3. (C) The viability for each of the mutant strains shown in panel B was determined by plating equal amounts of cells on galactose plates at different time points following the depletion of wild-type histone H3. The colonies formed on plates were scored after 72 h of incubation. Relative viability was calculated as the ratio of the colony number at certain time point to the 0-h time point. Each error bar represents the standard deviation of three independent experiments.