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Evolutionary engineering improves tolerance for medium-chain alcohols in Saccharomyces cerevisiae

Davis López, Stephanie A., Griffith, Douglas Andrew, Choi, Brian, Cate, Jamie H. D., Tullman-Ercek, Danielle
Biotechnology for biofuels 2018 v.11 no.1 pp. 90
Saccharomyces cerevisiae, biofuels, butanol, cost effectiveness, engineering, guanine, mutation, pentanols, petroleum, proteins, toxicity, translation (genetics)
BACKGROUND: Yeast-based chemical production is an environmentally friendly alternative to petroleum-based production or processes that involve harsh chemicals. However, many potential alcohol biofuels, such as n-butanol, isobutanol and n-hexanol, are toxic to production organisms, lowering the efficiency and cost-effectiveness of these processes. We set out to improve the tolerance of Saccharomyces cerevisiae toward these alcohols. RESULTS: We evolved the laboratory strain of S. cerevisiae BY4741 to be more tolerant toward n-hexanol and show that the mutations which confer tolerance occur in proteins of the translation initiation complex. We found that n-hexanol inhibits initiation of translation and evolved mutations in the α subunit of eIF2 and the γ subunit of its guanine exchange factor eIF2B rescue this inhibition. We further demonstrate that translation initiation is affected by other alcohols such as n-pentanol and n-heptanol, and that mutations in the eIF2 and eIF2B complexes greatly improve tolerance to these medium-chain alcohols. CONCLUSIONS: We successfully generated S. cerevisiae strains that have improved tolerance toward medium-chain alcohols and have demonstrated that the causative mutations overcome inhibition of translation initiation by these alcohols.