title: Identification of novel genes responsible for ethanol and/or thermotolerance by transposon mutagenesis in Saccharomyces cerevisiae.
abstract: Saccharomyces cerevisiae strains tolerant to ethanol and heat stresses are important for industrial ethanol production. In this study, five strains (Tn 1-5) tolerant to up to 15% ethanol were isolated by screening a transposon-mediated mutant library. Two of them displayed tolerance to heat (42 °C). The determination of transposon insertion sites and Northern blot analysis identified seven putative genes (CMP2, IMD4, SSK2, PPG1, DLD3, PAM1, and MSN2) and revealed simultaneous down-regulations of CMP2 and IMD4, and SSK2 and PPG1, down-regulation of DLD3, and disruptions of the open reading frame of PAM1 and MSN2, indicating that ethanol and/or heat tolerance can be conferred. Knockout mutants of these seven individual genes were ethanol tolerant and three of them (SSK2, PPG1, and PAM1) were tolerant to heat. Such tolerant phenotypes reverted to sensitive phenotypes by the autologous or overexpression of each gene. Five transposon mutants showed higher ethanol production and grew faster than the control strain when cultured in rich media containing 30% glucose and initial 6% ethanol at 30 °C. Of those, two thermotolerant transposon mutants (Tn 2 and Tn 3) exhibited significantly enhanced growth and ethanol production compared to the control at 42 °C. The genes identified in this study may provide a basis for the application in developing industrial yeast strains.
authors.affiliation: Department of Life Science, College of Natural Sciences, Ewha Womans University, 11-1, Daehyun-dong, Seodaemun-gu, Seoul 120-750, South Korea.
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Na-Rae
authors.initials: NR
authors.lastname: Kim
authors.forename: Jungwoo
authors.initials: J
authors.lastname: Yang
authors.forename: Wonja
authors.initials: W
authors.lastname: Choi
mesh_terms: D004251:DNA Transposable Elements; D000431:Ethanol / Q000633:toxicity*; D015870:Gene Expression; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D006358:Hot Temperature; D016254:Mutagenesis, Insertional / Q000379:methods*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development* / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol