title: Identification of an important motif that controls the activity and specificity of sugar transporters.
abstract: Efficient glucose-xylose co-utilization is critical for economical biofuel production from lignocellulosic biomass. To enable glucose-xylose co-utilization, a highly active xylose specific transporter without glucose inhibition is desirable. However, our understanding of the structure-activity/specificity relationship of sugar transporters in general is limited, which hinders our ability to engineer xylose-specific transporters. In this study, via homology modeling and analysis of hexose sugar transporter HXT14 mutants, we identified a highly conserved YYX(T/P) motif that plays an important role in controlling the activity and specificity of sugar transporters. We demonstrated that mutating the two tyrosine residues of the motif to phenylalanine, respectively, improved glucose transport capacity across several different sugar transporters. Furthermore, we illustrated that by engineering the fourth position in the YYX(T/P) motif, the sugar specificity of transporters was significantly altered or even reversed towards xylose. Finally, using the engineered sugar transporter, genuine glucose-xylose co-fermentation was achieved. Biotechnol. Bioeng. 2016;113: 1460-1467. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: School of Molecular and Cellular Biology, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Chenzhao
authors.initials: C
authors.lastname: Yu
authors.affiliation: Department of Chemical and Biomolecular Engineering, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois. zhao5@illinois.edu.|Department of Biochemistry, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois. zhao5@illinois.edu.|Departments of Chemistry and Bioengineering, Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana 61801, Illinois. zhao5@illinois.edu.
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhao
mesh_terms: D020816:Amino Acid Motifs; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014994:Xylose / Q000378:metabolism*
chemical_list: D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D014994:Xylose; D005947:Glucose
keywords: glucose-xylose co-fermentation; protein engineering; specificity; sugar transporter