title: Metabolic engineering of a synergistic pathway for n-butanol production in Saccharomyces cerevisiae.
abstract: n-Butanol has several favourable properties as an advanced fuel or a platform chemical. Bio-based production of n-butanol is becoming increasingly important for sustainable chemical industry. Synthesis of n-butanol can be achieved via more than one metabolic pathway. Here we report the metabolic engineering of Saccharomyces cerevisiae to produce n-butanol through a synergistic pathway: the endogenous threonine pathway and the introduced citramalate pathway. Firstly, we characterized and optimized the endogenous threonine pathway; then, a citramalate synthase (CimA) mediated pathway was introduced to construct the synergistic pathway; next, the synergistic pathway was optimized by additional overexpression of relevant genes identified previously; meanwhile, the n-butanol production was also improved by overexpression of keto-acid decarboxylases (KDC) and alcohol dehydrogenase (ADH). After combining these strategies with co-expression of LEU1 (two copies), LEU4, LEU2 (two copies), LEU5, CimA, NFS1, ADH7 and ARO10(*), we achieved an n-butanol production of 835 mg/L in the final engineered strain, which is almost 7-fold increase compared to the initial strain. Furthermore, the production showed a 3-fold of the highest titer ever reported in yeast. Therefore, the engineered yeast strain represents a promising alternative platform for n-butanol production.
authors.affiliation: Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore.
authors.forename: Shuobo
authors.initials: S
authors.lastname: Shi
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
authors.forename: Tong
authors.initials: T
authors.lastname: Si
authors.affiliation: Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore.
authors.forename: Zihe
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore.
authors.forename: Hongfang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore.
authors.forename: Ee Lui
authors.initials: EL
authors.lastname: Ang
authors.affiliation: Metabolic Engineering Research Laboratory, Science and Engineering Institutes, Agency for Science, Technology and Research, Singapore.|Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D020001:1-Butanol; D000426:Alcohol Dehydrogenase; D002262:Carboxy-Lyases