Journal Article Reconstruction of thermotolerant yeast by one-point mutation identified through whole-genome analyses of adaptively-evolved strains

Satomura, Atsushi  ,  Miura, Natsuko  ,  Kuroda, Kouichi  ,  Ueda, Mitsuyoshi

62016-03-17 , Nature Publishing Group
酵母の熱適応進化の大規模ゲノム解析によって熱耐性因子の同定に成功 -バイオエタノール生産性の飛躍的な向上に貢献-. 京都大学プレスリリース. 2016-03-22.
Saccharomyces cerevisiae is used as a host strain in bioproduction, because of its rapid growth, ease of genetic manipulation, and high reducing capacity. However, the heat produced during the fermentation processes inhibits the biological activities and growth of the yeast cells. We performed whole-genome sequencing of 19 intermediate strains previously obtained during adaptation experiments under heat stress; 49 mutations were found in the adaptation steps. Phylogenetic tree revealed at least five events in which these strains had acquired mutations in the CDC25 gene. Reconstructed CDC25 point mutants based on a parental strain had acquired thermotolerance without any growth defects. These mutations led to the downregulation of the cAMP-dependent protein kinase (PKA) signaling pathway, which controls a variety of processes such as cell-cycle progression and stress tolerance. The one-point mutations in CDC25 were involved in the global transcriptional regulation through the cAMP/PKA pathway. Additionally, the mutations enabled efficient ethanol fermentation at 39 °C, suggesting that the one-point mutations in CDC25 may contribute to bioproduction.

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