An engineered cryptic Hxt11 sugar transporter facilitates glucose–xylose co-consumption in Saccharomyces cerevisiae. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Shin, Hyun; Nijland, Jeroen; Waal, Paul; Jong, René; Klaassen, Paul; Driessen, Arnold
• Is Part Of: Biotechnology for biofuels. Volume 8:Issue 1(2015)
• Page Start: 1
• Page End: 13
• Publication Date: 2015-12
• Subjects: Sugar transport -- Directed evolution -- Lignocellulose conversion -- Yeast; Biotechnology -- Periodicals; Biomass energy -- Periodicals; Energy-Generating Resources -- Periodicals; 662.88
• DOI: 10.1186/s13068-015-0360-6
• Languages: English
• ISSNs: 1754-6834

Abstract

Abstract Background The yeastSaccharomyces cerevisiae is unable to ferment pentose sugars liked -xylose. Through the introduction of the respective metabolic pathway, S. cerevisiae is able to ferment xylose but first utilizesd -glucose before thed -xylose can be transported and metabolized. Low affinityd -xylose uptake occurs through the endogenous hexose (Hxt) transporters. For a more robust sugar fermentation, co-consumption ofd -glucose andd -xylose is desired asd -xylose fermentation is in particular prone to inhibition by compounds present in pretreated lignocellulosic feedstocks. Results Evolutionary engineering of ad -xylose-fermentingS. cerevisiae strain lacking the major transporterHXT1 –7 andGAL2 genes yielded a derivative that shows improved growth on xylose because of the expression of a normally crypticHXT11 gene. Hxt11 also supported improved growth ond -xylose by the wild-type strain. Further selection for glucose-insensitive growth ond -xylose employing a quadruple hexokinase deletion yielded mutations at N366 of Hxt11 that reversed the transporter specificity ford -glucose intod -xylose while maintaining highd -xylose transport rates. The Hxt11 mutant enabled the efficient co-fermentation of xylose and glucose at industrially relevant sugar concentrations when expressed in a strain lacking theHXT1 –7 andGAL2 genes. Conclusions Hxt11 is a cryptic sugar transporter ofS. cerevisiae that previously has not been associated with effectived -xylose transport. Mutagenesis of Hxt11 yielded transporters that show a better affinity ford -xylose as compared tod -glucose while maintaining high transport rates.d -glucose andd -xylose co-consumption is due to a redistribution of the sugar transport flux while maintaining the total sugar conversion rate into ethanol. This method provides a single transporter solution for effective fermentation on lignocellulosic feedstocks.