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An engineered cryptic Hxt11 sugar transporter facilitates glucose–xylose co-consumption in Saccharomyces cerevisiae
- Source :
- Biotechnology for Biofuels, 8(176). BioMed Central Ltd., Biotechnology for Biofuels
- Publication Year :
- 2015
- Publisher :
- Springer Science and Business Media LLC, 2015.
-
Abstract
- Background The yeast Saccharomyces cerevisiae is unable to ferment pentose sugars like d-xylose. Through the introduction of the respective metabolic pathway, S. cerevisiae is able to ferment xylose but first utilizes d-glucose before the d-xylose can be transported and metabolized. Low affinity d-xylose uptake occurs through the endogenous hexose (Hxt) transporters. For a more robust sugar fermentation, co-consumption of d-glucose and d-xylose is desired as d-xylose fermentation is in particular prone to inhibition by compounds present in pretreated lignocellulosic feedstocks. Results Evolutionary engineering of a d-xylose-fermenting S. cerevisiae strain lacking the major transporter HXT1–7 and GAL2 genes yielded a derivative that shows improved growth on xylose because of the expression of a normally cryptic HXT11 gene. Hxt11 also supported improved growth on d-xylose by the wild-type strain. Further selection for glucose-insensitive growth on d-xylose employing a quadruple hexokinase deletion yielded mutations at N366 of Hxt11 that reversed the transporter specificity for d-glucose into d-xylose while maintaining high d-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 the HXT1–7 and GAL2 genes. Conclusions Hxt11 is a cryptic sugar transporter of S. cerevisiae that previously has not been associated with effective d-xylose transport. Mutagenesis of Hxt11 yielded transporters that show a better affinity for d-xylose as compared to d-glucose while maintaining high transport rates. d-glucose and d-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. Electronic supplementary material The online version of this article (doi:10.1186/s13068-015-0360-6) contains supplementary material, which is available to authorized users.
- Subjects :
- STRAIN
GENES
YEAST HEXOSE TRANSPORTERS
Saccharomyces cerevisiae
INHIBITION
Pentose
METABOLISM
Management, Monitoring, Policy and Law
Xylose
Applied Microbiology and Biotechnology
chemistry.chemical_compound
ETHANOL-PRODUCTION
Sugar transporter
Sugar
LIGNOCELLULOSE
chemistry.chemical_classification
FERMENTATION
biology
Lignocellulose conversion
Renewable Energy, Sustainability and the Environment
Research
food and beverages
CANDIDA-INTERMEDIA
PERFORMANCE
biology.organism_classification
Yeast
Metabolic pathway
General Energy
Biochemistry
chemistry
Sugar transport
Directed evolution
Fermentation
Biotechnology
Subjects
Details
- ISSN :
- 17546834
- Volume :
- 8
- Database :
- OpenAIRE
- Journal :
- Biotechnology for Biofuels
- Accession number :
- edsair.doi.dedup.....e7c1fc1339a00473e8e2ce205b0f67e7