title: Sorbitol dehydrogenase is a cytosolic protein required for sorbitol metabolism in Arabidopsis thaliana.
abstract: Sorbitol is converted to fructose in Rosaceae species by SORBITOL DEHYDROGENASE (SDH, EC 1.1.1.14), especially in sink organs. SDH has also been found in non-Rosaceae species and here we show that the protein encoded by At5g51970 in Arabidopsis thaliana (L.) Heynh. possesses the molecular characteristics of an SDH. Using a green fluorescent protein-tagged version and anti-SDH antisera, we determined that SDH is cytosolically localized, consistent with bioinformatic predictions. We also show that SDH is widely expressed, and that SDH protein accumulates in both source and sink organs. In the presence of NAD+, recombinant SDH exhibited greatest oxidative activity with sorbitol, ribitol and xylitol as substrates; other sugar alcohols were oxidized to a lesser extent. Under standard growth conditions, three independent sdh- mutants developed as wild-type. Nevertheless, all three exhibited reduced dry weight and primary root length compared to wild-type when grown in the presence of sorbitol. Additionally, under short-day conditions, the mutants were more resistant to dehydration stress, as shown by a reduced loss of leaf water content when watering was withheld, and a greater survival rate on re-watering. This evidence suggests that limitations in the metabolism of sugar alcohols alter the growth of Arabidopsis and its response to drought.
authors.affiliation: Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile. igneea@hotmail.com
authors.forename: María Francisca
authors.initials: MF
authors.lastname: Aguayo
authors.forename: Diego
authors.initials: D
authors.lastname: Ampuero
authors.forename: Patricio
authors.initials: P
authors.lastname: Mandujano
authors.forename: Roberto
authors.initials: R
authors.lastname: Parada
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Muñoz
authors.forename: Marta
authors.initials: M
authors.lastname: Gallart
authors.forename: Teresa
authors.initials: T
authors.lastname: Altabella
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cabrera
authors.forename: Claudia
authors.initials: C
authors.lastname: Stange
authors.forename: Michael
authors.initials: M
authors.lastname: Handford
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D003600:Cytosol / Q000201:enzymology; D003681:Dehydration; D035264:Flowers / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D007700:Kinetics; D007064:L-Iditol 2-Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009243:NAD / Q000378:metabolism; D009928:Organ Specificity; D010641:Phenotype; D018515:Plant Leaves / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D018517:Plant Roots / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D018547:Plant Stems / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins; D012255:Ribitol / Q000378:metabolism; D012639:Seeds / Q000201:enzymology / Q000254:growth & development / Q000648:ultrastructure; D016415:Sequence Alignment; D013012:Sorbitol / Q000378:metabolism*; D014993:Xylitol / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; D009243:NAD; D012255:Ribitol; D013012:Sorbitol; D007064:L-Iditol 2-Dehydrogenase; D014993:Xylitol