title: Identification of target genes conferring ethanol stress tolerance to Saccharomyces cerevisiae based on DNA microarray data analysis.
abstract: During industrial production process using yeast, cells are exposed to the stress due to the accumulation of ethanol, which affects the cell growth activity and productivity of target products, thus, the ethanol stress-tolerant yeast strains are highly desired. To identify the target gene(s) for constructing ethanol stress tolerant yeast strains, we obtained the gene expression profiles of two strains of Saccharomyces cerevisiae, namely, a laboratory strain and a strain used for brewing Japanese rice wine (sake), in the presence of 5% (v/v) ethanol, using DNA microarray. For the selection of target genes for breeding ethanol stress tolerant strains, clustering of DNA microarray data was performed. For further selection, the ethanol sensitivity of the knockout mutants in each of which the gene selected by DNA microarray analysis is deleted, was also investigated. The integration of the DNA microarray data and the ethanol sensitivity data of knockout strains suggests that the enhancement of expression of genes related to tryptophan biosynthesis might confer the ethanol stress tolerance to yeast cells. Indeed, the strains overexpressing tryptophan biosynthesis genes showed a stress tolerance to 5% ethanol. Moreover, the addition of tryptophan to the culture medium and overexpression of tryptophan permease gene conferred ethanol stress tolerance to yeast cells. These results indicate that overexpression of the genes for trypophan biosynthesis increases the ethanol stress tolerance. Tryptophan supplementation to culture and overexpression of the tryptophan permease gene are also effective for the increase in ethanol stress tolerance. Our methodology for the selection of target genes for constructing ethanol stress tolerant strains, based on the data of DNA microarray analysis and phenotypes of knockout mutants, was validated.
authors.affiliation: Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirasawa
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yoshikawa
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakakura
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nagahisa
authors.forename: Chikara
authors.initials: C
authors.lastname: Furusawa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Katakura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
authors.forename: Suteaki
authors.initials: S
authors.lastname: Shioya
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D026905:Amino Acid Transport Systems / Q000235:genetics; D016000:Cluster Analysis; D000431:Ethanol / Q000494:pharmacology*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005800:Genes, Fungal; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014364:Tryptophan / Q000096:biosynthesis
chemical_list: D026905:Amino Acid Transport Systems; D029701:Saccharomyces cerevisiae Proteins; C429825:TAT2 protein, S cerevisiae; D000431:Ethanol; D014364:Tryptophan