Fig. 5

ZbHaa1 is required for acetic acid induced transcriptional activation of Z. bailii genes demonstrated to be homologous to S. cerevisiae Haa1 target genes. a Growth curves of Z. bailii IST302 (●,○) and of its derived deletion mutant Zbhaa1∆ (▲,△) cultivated in MM medium, pH 4.0 (filled symbols) or in the same medium supplemented with acetic acid (empty symbols). Acetic acid was added after 1 h of growth of exponential cells prepared under standard conditions in MM medium to a final concentration of 140 mM. Yeast cells were harvested before acetic acid supplementation (Time point 0) and 1 h after acetic acid addition (Time point 1). Comparison of the transcript levels from b ZbHAA1, and c ZbMSN4, ZbHRK1, ZbHSP30, ZbTPO3, ZbYGP1 and ZbYRO2 in Z. bailii IST302 (dark bars) or in the derived deletion mutant Zbhaa1∆ (grey bars) in the absence of acetic acid (Time point 0) and 1 h after acetic acid supplementation (Time point 1). ZbACT1 mRNA level was used as an internal control. The mRNA level from Z. bailii IST302 genes ZbHAA1, ZbMSN4, ZbHRK1, ZbHSP30, ZbTPO3, ZbYGP1 and ZbYRO2 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