(A) Chronological aging of methionine prototroph (MET+), semi-auxotroph (Δmet15) and auxotroph (Δmet2) isogenic yeast strains in SCD media supplemented with all amino acids (aa). Cell survival was estimated as colony formation of 500 cells plated at given time points, normalized to cell survival on day one (n = 4). (B) Chronological aging of Δmet15 strain, in SCD media supplemented with all aa except for methionine which was added at given concentrations. Cell survival of 500 cells plated at given time points, normalized to cell survival on day one (n = 4). (C) MET2 deletion strain (Δmet2) was grown to stationary phase in SCD (supplemented with all aa) and shifted to SCD media with different methionine concentrations. Cell survival of 500 cells plated at given time points, normalized to cell survival before the shift (n = 4). (D) Day 8 from experiment shown in C (n = 4). (E) Chronological aging of EUROSCARF BY4741 (also used above as Δmet15 reference strain) and mating type α wild type strain BY4742, as well as a methionine semi-auxotrophic variant thereof (BY4742 Δmet15), in SCD media supplemented with all aa. Cell survival of 500 cells plated at given time points, normalized to cell survival on day one (n = 3). See also Figure S1.