The amino-terminal tail of Hxt11 confers membrane stability to the Hxt2 sugar transporter and improves xylose fermentation in the presence of acetic acid

5 years ago

The amino-terminal tail of Hxt11 confers membrane stability to the Hxt2 sugar transporter and improves xylose fermentation in the presence of acetic acid

Paul P. de Waal, Jeroen G. Nijland, Hyun Yong Shin, Arnold J. M. Driessen

Hxt2 is a glucose repressed, high affinity glucose transporter of the yeast Saccharomyces cerevisiae and is subjected to high glucose induced degradation. Hxt11 is a sugar transporter that is stably expressed at the membrane irrespective the sugar concentration. To transfer this property to Hxt2, the N-terminal tail of Hxt2 was replaced by the corresponding region of Hxt11 yielding a chimeric Hxt11/2 transporter. This resulted in the stable expression of Hxt2 at the membrane and improved the growth on 8% d-glucose and 4% d-xylose. Mutation of N361 of Hxt11/2 into threonine reversed the specificity for d-xylose over d-glucose with high d-xylose transport rates. This mutant supported efficient sugar fermentation of both d-glucose and d-xylose at industrially relevant sugar concentrations even in the presence of the inhibitor acetic acid which is normally present in lignocellulosic hydrolysates. Biotechnol. Bioeng. 2017;114: 1937–1945. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. Hxt2 is a high affinity glucose transporter of the yeast Saccharomyces cerevisiae and degraded at high glucose concentration. Shin and coworkers replaced the N-terminus of Hxt2 for the corresponding region of Hxt11, causing stable membrane expression of this transporter even at high glucose concentration. Further mutagenesis of the Hxt11/2 chimer resulted in a transporter that supports co-fermentation of glucose and xylose.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/bit.26322