Critical Roles of the Pentose Phosphate Pathway and GLN3 in Isobutanol-Specific Tolerance in Yeast.

TitleCritical Roles of the Pentose Phosphate Pathway and GLN3 in Isobutanol-Specific Tolerance in Yeast.
Publication TypeJournal Article
Year of Publication2019
AuthorsKuroda, K, Hammer, SK, Watanabe, Y, López, JMontaño, Fink, GR, Stephanopoulos, G, Ueda, M, Avalos, JL
JournalCell Syst
Date Published2019 Dec 18
KeywordsBiofuels, Butanols, Ethanol, Fermentation, Gene Deletion, Genetic Engineering, Nitrogen, Pentose Phosphate Pathway, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Transcription Factors, Transcriptional Activation

<p>Branched-chain alcohols are attractive advanced biofuels; however, their cellular toxicity is an obstacle to engineering microbes to produce them at high titers. We performed genome-wide screens on the Saccharomyces cerevisiae gene deletion library to identify cell systems involved in isobutanol-specific tolerance. Deletion of pentose phosphate pathway genes GND1 or ZWF1 causes hypersensitivity to isobutanol but not to ethanol. By contrast, deletion of GLN3 increases yeast tolerance specifically to branched-chain alcohols. Transcriptomic analyses revealed that isobutanol induces a nitrogen starvation response via GLN3 and GCN4, upregulating amino acid biosynthesis and nitrogen scavenging while downregulating glycolysis, cell wall biogenesis, and membrane lipid biosynthesis. Disruption of this response by deleting GLN3 is enough to enhance tolerance and boost isobutanol production 4.9-fold in engineered strains. This study illustrates how adaptive mechanisms to tolerate stress can lead to toxicity in microbial fermentations for chemical production and how genetic interventions can boost production by evading such mechanisms.</p>

Alternate JournalCell Syst
PubMed ID31734159
Grant ListR01 GM035010 / GM / NIGMS NIH HHS / United States