Fig. 3

Like ScHaa1, ZbHaa1 is able to mediate the transcriptional activation of YGP1 in S. cerevisiae under acetic acid stress. The effect that the expression of ZbHAA1 or ScHAA1 in S. cerevisiae haa1∆ has in the transcript levels from the ScHaa1 target gene YGP1 was compared. a Growth curves of S. cerevisiae BY4741 parental strain transformed with the cloning vector (●,○) and of its derived deletion mutant haa1∆ expressing the recombinant plasmids pG_ZbHAA1-IST (♦,◇), pG_ScHAA1 (▲,△) or the cloning vector (■, □) cultivated in MM4-U (filled symbols) or in the same medium supplemented with acetic acid (empty symbols). Yeast cells were harvested before acetic acid supplementation (Time point 0), or 1 or 2 h after acetic acid addition (Time points 1 and 2, respectively). b Transcript levels from HAA1 in S. cerevisiae BY4741 transformed with the cloning vector (black bar), in S. cerevisiae deletion mutant haa1∆ transformed with the cloning vector (ND-not detected), or expressing ScHAA1 (dark grey bar). c Transcript levels from YGP1 in S. cerevisiae BY4741 transformed with the cloning vector (black bar), in S. cerevisiae deletion mutant haa1∆ transformed with the cloning vector (light grey bar), or expressing ScHAA1 (dark grey bar) or ZbHAA1 (white bar). ACT1 mRNA level was used as an internal control. The mRNA levels from HAA1 and YGP1 genes in S. cerevisiae BY4741 transformed with the cloning vector in the absence of acetic acid (Time point 0) were set as 1 and the transcript levels from those genes were calculated relative to this control. mRNA values shown are the mean of, at least, three independent experiments. Results were analysed by two-way ANOVA. (*) p-value below 0.05, when comparing the relative mRNA levels in each strain at a given time point