title: Isobutanol production in engineered Saccharomyces cerevisiae by overexpression of 2-ketoisovalerate decarboxylase and valine biosynthetic enzymes.
abstract: Engineering of Saccharomyces cerevisiae to produce advanced biofuels such as isobutanol has received much attention because this yeast has a natural capacity to produce higher alcohols. In this study, construction of isobutanol production systems was attempted by overexpression of effective 2-keto acid decarboxylase (KDC) and combinatorial overexpression of valine biosynthetic enzymes in S. cerevisiae D452-2. Among the six putative KDC enzymes from various microorganisms, 2-ketoisovalerate decarboxylase (Kivd) from L. lactis subsp. lactis KACC 13877 was identified as the most suitable KDC for isobutanol production in the yeast. Isobutanol production by the engineered S. cerevisiae was assessed in micro-aerobic batch fermentations using glucose as a sole carbon source. 93 mg/L isobutanol was produced in the Kivd overexpressing strain, which corresponds to a fourfold improvement as compared with the control strain. Isobutanol production was further enhanced to 151 mg/L by additional overexpression of acetolactate synthase (Ilv2p), acetohydroxyacid reductoisomerase (Ilv5p), and dihydroxyacid dehydratase (Ilv3p) in the cytosol.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Won-Heong
authors.initials: WH
authors.lastname: Lee
authors.forename: Seung-Oh
authors.initials: SO
authors.lastname: Seo
authors.forename: Yi-Hyun
authors.initials: YH
authors.lastname: Bae
authors.forename: Hong
authors.initials: H
authors.lastname: Nan
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Seo
mesh_terms: D015072:2-Acetolactate Mutase / Q000096:biosynthesis / Q000235:genetics; D000095:Acetolactate Synthase / Q000096:biosynthesis / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D000440:Butanols / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000096:biosynthesis* / Q000235:genetics; D006836:Hydro-Lyases / Q000096:biosynthesis / Q000235:genetics; D013294:Lactococcus lactis / Q000201:enzymology / Q000235:genetics; D060847:Metabolic Engineering; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D014633:Valine / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D000440:Butanols; C040507:isobutyl alcohol; D000095:Acetolactate Synthase; D002262:Carboxy-Lyases; D006836:Hydro-Lyases; C020052:dihydroxyacid dehydratase; D015072:2-Acetolactate Mutase; D014633:Valine