Xylene causes oxidative stress and pronounced translation repression in Saccharomyces cerevisiae

Organic solvent-resistant microorganisms are strongly desired for efficient fermentative production of hydrophobic substances in water-organic solvent two-phase systems. To improve organic solvent-resistance of microorganisms, a better understanding of the effects of organic solvents on microbial cells and cellular responses to organic solvents is essential. So far, various bacteria have been studied for their response mechanisms against organic solvents and improvement of their resistance to organic solvents. On the other hand, limited information is available on the effects of organic solvents on eukaryotic microorganisms. We herein examined the physiological effects of xylene, one of representative organic solvents, on the budding yeast Saccharomyces cerevisiae. We found that xylene induced fragmentation of mitochondria and the nuclear accumulation of Yap1, an oxidative stress responsive transcription factor, followed by the transcriptional activation of its target genes, GPX2 and TRX2, in yeast cells treated with xylene. These findings indicate that xylene caused oxidative stress in yeast cells. However, treatment with 0.03% (v/v) or more of xylene severely repressed the translation activity of yeast cells. Therefore, the expected protein synthesis of Yap1-target genes was not observed despite the transcriptional activation in cells treated with 0.03% (v/v) xylene. This is the first report on the inhibitory effects of xylene on bulk translation activity and provides novel insights into the toxicity of xylene.