title: Identification of glucose transporters in Aspergillus nidulans.
abstract: To characterize the mechanisms involved in glucose transport, in the filamentous fungus Aspergillus nidulans, we have identified four glucose transporter encoding genes hxtB-E. We evaluated the ability of hxtB-E to functionally complement the Saccharomyces cerevisiae EBY.VW4000 strain that is unable to grow on glucose, fructose, mannose or galactose as single carbon source. In S. cerevisiae HxtB-E were targeted to the plasma membrane. The expression of HxtB, HxtC and HxtE was able to restore growth on glucose, fructose, mannose or galactose, indicating that these transporters accept multiple sugars as a substrate through an energy dependent process. A tenfold excess of unlabeled maltose, galactose, fructose, and mannose were able to inhibit glucose uptake to different levels (50 to 80 %) in these s. cerevisiae complemented strains. Moreover, experiments with cyanide-m-chlorophenylhydrazone (CCCP), strongly suggest that hxtB, -C, and -E mediate glucose transport via active proton symport. The A. nidulans ΔhxtB, ΔhxtC or ΔhxtE null mutants showed ~2.5-fold reduction in the affinity for glucose, while ΔhxtB and -C also showed a 2-fold reduction in the capacity for glucose uptake. The ΔhxtD mutant had a 7.8-fold reduction in affinity, but a 3-fold increase in the capacity for glucose uptake. However, only the ΔhxtB mutant strain showed a detectable decreased rate of glucose consumption at low concentrations and an increased resistance to 2-deoxyglucose.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Thaila Fernanda
authors.initials: TF
authors.lastname: Dos Reis
authors.forename: João Filipe
authors.initials: JF
authors.lastname: Menino
authors.forename: Vinícius Leite Pedro
authors.initials: VL
authors.lastname: Bom
authors.forename: Neil Andrew
authors.initials: NA
authors.lastname: Brown
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Colabardini
authors.forename: Marcela
authors.initials: M
authors.lastname: Savoldi
authors.forename: Maria Helena S
authors.initials: MH
authors.lastname: Goldman
authors.forename: Fernando
authors.initials: F
authors.lastname: Rodrigues
authors.forename: Gustavo Henrique
authors.initials: GH
authors.lastname: Goldman
mesh_terms: D001233:Aspergillus nidulans / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D005800:Genes, Fungal; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development
chemical_list: D002250:Carbon Radioisotopes; D009004:Monosaccharide Transport Proteins