Figure 3.

Hxk2p-S15 to Hxk2p-A15 mutation suppresses the phenotypes of sit4Δ cells. SIT4 gene was deleted in S. cerevisiae WAY.78-1 cells expressing wild type (Hxk2p-S15) or mutant (Hxk2p-S15A) hexokinase 2. (A) Oxygen consumption rates were measured as described in Materials and Methods using exponential phase cells grown in YPD medium. (B) Chronological lifespan was assessed by following the survival of cells maintained in the growth medium overtime. Cellular viability was measured at 2 to 3 d intervals and was expressed as % colony forming units (aged vs day 0). Values are mean ± SD of at least 3 independent experiments. (C) Oxidative stress resistance was assessed in cells were treated with 0.5 mM H₂O₂ for 30 min. Cell viability was determined by standard dilution plate counts and expressed as the percentage of the colony-forming units of non-stressed cells. Values are means ± SD of 3 independent experiments. *p < 0.05, **p < 0.01; Student's t-test. (D) Growth curves. (E) Cell cycle. Yeast cells were labeled with propidium iodide and analyzed by flow cytometry. The experiments were reproduced 3 times, using independent samples. A representative experiment is shown. (F) Quantification of the percentage of cells in the different phases of the cell cycle [from (E)].