title: OmZnT1 and OmFET, two metal transporters from the metal-tolerant strain Zn of the ericoid mycorrhizal fungus Oidiodendron maius, confer zinc tolerance in yeast.
abstract: Two full-length cDNAs (OmZnT1 and OmFET) encoding membrane transporters were identified by yeast functional screening in the heavy metal tolerant ericoid mycorrhizal isolate Oidiodendron maius Zn. OmZnT1 belongs to the Zn-Type subfamily of the cation diffusion facilitators, whereas OmFET belongs to the family of iron permeases. Their properties were investigated in yeast by functional complementation of mutants affected in metal uptake and metal tolerance. Heterologous expression of OmZnT1 and OmFET in a Zn-sensitive yeast mutant restored the wild-type phenotype. Additionally, OmZnT1 expression also restored cobalt tolerance in a Co-sensitive mutant. A GFP fusion protein revealed that OmZnT1 was targeted to the endoplasmic reticulum membrane, a result consistent with a function for OmZnT1 in metal sequestration. Similarly to other iron permeases, OmFET-GFP was localized on the plasma membrane. OmFET restored the growth of uptake-defective strains for iron and zinc. Zinc-sensitive yeast mutants expressing OmFET specifically accumulated magnesium, as compared to cells transformed with the empty vector. We suggest that OmFET may counteract zinc toxicity by increasing entry of magnesium into the cell.
authors.affiliation: University of Turin, Department of Life Sciences and Systems Biology, Viale Mattioli 25, Torino I-10125, Italy.
authors.forename: Hassine Radhouane
authors.initials: HR
authors.lastname: Khouja
authors.forename: Simona
authors.initials: S
authors.lastname: Abbà
authors.forename: Laurence
authors.initials: L
authors.lastname: Lacercat-Didier
authors.forename: Stefania
authors.initials: S
authors.lastname: Daghino
authors.forename: Didier
authors.initials: D
authors.lastname: Doillon
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.forename: Elena
authors.initials: E
authors.lastname: Martino
authors.forename: Marta
authors.initials: M
authors.lastname: Vallino
authors.forename: Silvia
authors.initials: S
authors.lastname: Perotto
authors.forename: Michel
authors.initials: M
authors.lastname: Chalot
authors.forename: Damien
authors.initials: D
authors.lastname: Blaudez
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D000075322:Heavy Metal Poisoning; D007501:Iron / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011041:Poisoning; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D049452:Green Fluorescent Proteins; D007501:Iron; D015032:Zinc