title: Hxt13, Hxt15, Hxt16 and Hxt17 from Saccharomyces cerevisiae represent a novel type of polyol transporters.
abstract: The genome of S. cerevisae encodes at least twenty hexose transporter-like proteins. Despite extensive research, the functions of Hxt8-Hxt17 have remained poorly defined. Here, we show that Hxt13, Hxt15, Hxt16 and Hxt17 transport two major hexitols in nature, mannitol and sorbitol, with moderate affinities, by a facilitative mechanism. Moreover, Hxt11 and Hxt15 are capable of transporting xylitol, a five-carbon polyol derived from xylose, the most abundant pentose in lignocellulosic biomass. Hxt11, Hxt13, Hxt15, Hxt16 and Hxt17 are phylogenetically and functionally distinct from known polyol transporters. Based on docking of polyols to homology models of transporters, we propose the architecture of their active site. In addition, we determined the kinetic parameters of mannitol and sorbitol dehydrogenases encoded in the yeast genome, showing that they discriminate between mannitol and sorbitol to a much higher degree than the transporters.
authors.affiliation: Institute of Molecular Biosciences, Goethe University, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany.
authors.forename: Paulina
authors.initials: P
authors.lastname: Jordan
authors.affiliation: Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
authors.forename: Jun-Yong
authors.initials: JY
authors.lastname: Choe
authors.affiliation: Institute of Molecular Biosciences, Goethe University, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Boles
authors.affiliation: Institute of Molecular Biosciences, Goethe University, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany.
authors.forename: Mislav
authors.initials: M
authors.lastname: Oreb
mesh_terms: D007064:L-Iditol 2-Dehydrogenase / Q000378:metabolism*; D008353:Mannitol / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D062105:Molecular Docking Simulation; D009004:Monosaccharide Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D013012:Sorbitol / Q000378:metabolism*
chemical_list: C000589397:HXT13 protein, S cerevisiae; C104400:HXT15 protein, S cerevisiae; C000613311:Hxt16 protein, S cerevisiae; C000613312:Hxt17 protein, S cerevisiae; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D008353:Mannitol; D013012:Sorbitol; D007064:L-Iditol 2-Dehydrogenase