Yeast strains and plasmids used in this work are listed in Supplementary Table S1 . The transformation procedure was as described (28) . Strains were grown at 308C either in YPD, YPGal or YPGly medium (1% yeast extract, 2% Bacto-peptone, 2% glucose or 2% galactose or 2% glycerol, respectively) or in synthetic complete medium (SC, 0.67% yeast nitrogen base, 2% glucose or 2% galactose, supplemented with required amount of amino acids and nucleotide bases). Strains W303-1A-Bax, W303-1A-Bcl-x L , W303-rDNA were grown in SC media without leucine, tryptophan or uracil, respectively.