title: Tolerance to furfural-induced stress is associated with pentose phosphate pathway genes ZWF1, GND1, RPE1, and TKL1 in Saccharomyces cerevisiae.
abstract: Engineering yeast to be more tolerant to fermentation inhibitors, furfural and 5-hydroxymethylfurfural (HMF), will lead to more efficient lignocellulose to ethanol bioconversion. To identify target genes involved in furfural tolerance, a Saccharomyces cerevisiae gene disruption library was screened for mutants with growth deficiencies in the presence of furfural. It was hypothesized that overexpression of these genes would provide a growth benefit in the presence of furfural. Sixty two mutants were identified whose corresponding genes function in a wide spectrum of physiological pathways, suggesting that furfural tolerance is a complex process. We focused on four mutants, zwf1, gnd1, rpe1, and tkl1, which represent genes encoding pentose phosphate pathway (PPP) enzymes. At various concentrations of furfural and HMF, a clear association with higher sensitivity to these inhibitors was demonstrated in these mutants. PPP mutants were inefficient at reducing furfural to the less toxic furfuryl alcohol, which we propose is a result of an overall decreased abundance of reducing equivalents or to NADPH's role in stress tolerance. Overexpression of ZWF1 in S. cerevisiae allowed growth at furfural concentrations that are normally toxic. These results demonstrate a strong relationship between PPP genes and furfural tolerance and provide additional putative target genes involved in furfural tolerance.
authors.affiliation: National Center for Agriculture Utilization Research, Agriculture Research Service, USDA, Peoria, IL, USA. gorsichs@ncaur.usda.gov
authors.forename: S W
authors.initials: SW
authors.lastname: Gorsich
authors.forename: B S
authors.initials: BS
authors.lastname: Dien
authors.forename: N N
authors.initials: NN
authors.lastname: Nichols
authors.forename: P J
authors.initials: PJ
authors.lastname: Slininger
authors.forename: Z L
authors.initials: ZL
authors.lastname: Liu
authors.forename: C D
authors.initials: CD
authors.lastname: Skory
mesh_terms: D002238:Carbohydrate Epimerases / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D005662:Furaldehyde / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015966:Gene Expression Regulation, Fungal; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D008031:Lignin / Q000378:metabolism; D009154:Mutation; D010427:Pentose Phosphate Pathway; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D014174:Transketolase / Q000235:genetics / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C036909:lignocellulose; C008046:5-hydroxymethylfurfural; D002482:Cellulose; D008031:Lignin; D005662:Furaldehyde; D005954:Glucosephosphate Dehydrogenase; C084088:TKL1 protein, S cerevisiae; D014174:Transketolase; D002238:Carbohydrate Epimerases; C022554:L-ribulosephosphate 4-epimerase