title: Metabolically engineered Saccharomyces cerevisiae for branched-chain ester productions.
abstract: Medium branched-chain esters can be used not only as a biofuel but are also useful chemicals with various industrial applications. The development of economically feasible and environment friendly bio-based fuels requires efficient cell factories capable of producing desired products in high yield. Herein, we sought to use a number of strategies to engineer Saccharomyces cerevisiae for high-level production of branched-chain esters. Mitochondrion-based expression of ATF1 gene in a base strain with an overexpressed valine biosynthetic pathway together with expression of mitochondrion-relocalized α-ketoacid decarboxylase (encoded by ARO10) and alcohol dehydrogenase (encoded by ADH7) not only produced isobutyl acetate, but also 3-methyl-1-butyl acetate and 2-methyl-1-butyl acetate. Further segmentation of the downstream esterification step into the cytosol to utilize the cytosolic acetyl-CoA pool for acetyltransferase (ATF)-mediated condensation enabled an additional fold improvement of ester productions. The best titre attained in the present study is 260.2mg/L isobutyl acetate, 296.1mg/L 3-methyl-1-butyl acetate and 289.6mg/L 2-methyl-1-butyl acetate.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore; Temasek Laboratories, National University of Singapore, T-Lab Building 5A, Singapore 117411, Singapore; Present address: Biotransformation Innovation Platform, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. Electronic address: jifeng_yuan@biotrans.a-star.edu.sg.
authors.forename: Jifeng
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Pranjul
authors.initials: P
authors.lastname: Mishra
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore; Temasek Laboratories, National University of Singapore, T-Lab Building 5A, Singapore 117411, Singapore; Singapore Institute of Technology, 10 Dover Drive, Singapore 138683, Singapore.
authors.forename: Chi Bun
authors.initials: CB
authors.lastname: Ching
mesh_terms: D004926:Escherichia coli; D004952:Esters / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways; D011506:Proteins; D011773:Pyruvates / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
chemical_list: D004952:Esters; D011506:Proteins; D011773:Pyruvates; C079238:alcohol O-acetyltransferase
keywords: Branched-chain esters; Ehrlich degradation pathway; Pathway segmentation; Pyruvate carrier; Pyruvate shunt; Saccharomyces cerevisiae