title: GSF2 deletion increases lactic acid production by alleviating glucose repression in Saccharomyces cerevisiae.
abstract: Improving lactic acid (LA) tolerance is important for cost-effective microbial production of LA under acidic fermentation conditions. Previously, we generated LA-tolerant D-LA-producing S. cerevisiae strain JHY5310 by laboratory adaptive evolution of JHY5210. In this study, we performed whole genome sequencing of JHY5310, identifying four loss-of-function mutations in GSF2, SYN8, STM1, and SIF2 genes, which are responsible for the LA tolerance of JHY5310. Among the mutations, a nonsense mutation in GSF2 was identified as the major contributor to the improved LA tolerance and LA production in JHY5310. Deletion of GSF2 in the parental strain JHY5210 significantly improved glucose uptake and D-LA production levels, while derepressing glucose-repressed genes including genes involved in the respiratory pathway. Therefore, more efficient generation of ATP and NAD+via respiration might rescue the growth defects of the LA-producing strain, where ATP depletion through extensive export of lactate and proton is one of major reasons for the impaired growth. Accordingly, alleviation of glucose repression by deleting MIG1 or HXK2 in JHY5210 also improved D-LA production. GSF2 deletion could be applied to various bioprocesses where increasing biomass yield or respiratory flux is desirable.
authors.affiliation: School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Baek
authors.affiliation: School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
authors.forename: Eunice Y
authors.initials: EY
authors.lastname: Kwon
authors.affiliation: Personalized Genomic Medicine Research Center, KRIBB, 125 Gwahag-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Seon-Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
authors.forename: Ji-Sook
authors.initials: JS
authors.lastname: Hahn
mesh_terms: D057465:Catabolite Repression / Q000235:genetics; D019143:Evolution, Molecular; D017353:Gene Deletion; D016681:Genome, Fungal; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D009243:NAD / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C120037:Gsf2 protein, S cerevisiae; C085976:MIG1 protein, S cerevisiae; D008565:Membrane Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D009243:NAD; D019344:Lactic Acid; C490214:HXK2 protein, S cerevisiae; D006593:Hexokinase; D005947:Glucose