Analogously, our results show that the CtsR regulon was partially induced after 30 min and 24 h of ethanol exposure and included elevated expression of ClpP-, ClpE-, and Hsp1-encoding genes. This finding suggests that the chaperonin function of GroELS was not sufficient to sustain the correct folding of proteins during ethanol stress, and the accumulation of denatured and aggregated proteins resulted in the activation of Clp-mediated proteolysis (20).