Engineering of an endogenous hexose transporter into a specific D-xylose transporter facilitates glucose-xylose co-consumption in Saccharomyces cerevisiae

• Published in: Biotechnology for biofuels Vol. 7; no. 1; p. 168
• Main Authors: Nijland, Jeroen G, Shin, Hyun Yong, de Jong, René M, de Waal, Paul P, Klaassen, Paul, Driessen, Arnold JM
• Format: Journal Article
• Language: English
• Published: England Springer-Verlag 2014; BioMed Central Ltd; BioMed Central
• Subjects: Affinity; Biodiesel fuels; biofuels; carbon; chimerism; cost effectiveness; engineering; Ethanol; ethanol production; Glucose; hexokinase; Hexoses; lignocellulose; metabolism; mutation; Pentose; pentoses; Saccharomyces cerevisiae; Strain; Transporter; transporters; Uptakes; xylose; Yeast; yeasts; Netherlands; Sugar transporter; Bioethanol; Xylose transporter; Evolutionary engineering; Yeast
• ISSN: 1754-6834; 1754-6834
• DOI: 10.1186/s13068-014-0168-9

BACKGROUND: Engineering of Saccharomyces cerevisiae for the simultaneous utilization of hexose and pentose sugars is vital for cost-efficient cellulosic bioethanol production. This yeast lacks specific pentose transporters and depends on endogenous hexose transporters for low affinity pentose uptake. Consequently, engineered xylose-fermenting yeast strains first utilize D-glucose before D-xylose can be transported and metabolized. RESULTS: We have used an evolutionary engineering approach that depends on a quadruple hexokinase deletion xylose-fermenting S. cerevisiae strain to select for growth on D-xylose in the presence of high D-glucose concentrations. This resulted in D-glucose-tolerant growth of the yeast of D-xylose. This could be attributed to mutations at N367 in the endogenous chimeric Hxt36 transporter, causing a defect in D-glucose transport while still allowing specific uptake of D-xylose. The Hxt36-N367A variant transports D-xylose with a high rate and improved affinity, enabling the efficient co-consumption of D-glucose and D-xylose. CONCLUSIONS: Engineering of yeast endogenous hexose transporters provides an effective strategy to construct glucose-insensitive xylose transporters that are well integrated in the carbon metabolism regulatory network, and that can be used for efficient lignocellulosic bioethanol production.