University of Turin, Department of Life Sciences and Systems Biology, Viale Mattioli 25, Torino I-10125, Italy.
Fungal Genet Biol. 2013 Mar;52:53-64. doi: 10.1016/j.fgb.2012.11.004. Epub 2012 Dec 8.
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.
通过对重金属耐受型内生菌 Oidiodendron maius Zn 的酵母功能筛选，鉴定出两个全长 cDNA（OmZnT1 和 OmFET），它们分别编码膜转运蛋白。OmZnT1 属于阳离子扩散促进剂的 Zn 型亚家族，而 OmFET 属于铁透性酶家族。通过对金属摄取和金属耐受突变体的功能互补，在酵母中研究了它们的特性。OmZnT1 和 OmFET 在 Zn 敏感酵母突变体中的异源表达恢复了野生型表型。此外，OmZnT1 的表达还恢复了 Co 敏感突变体对钴的耐受性。GFP 融合蛋白表明 OmZnT1 靶向内质网膜，这与 OmZnT1 在金属螯合中的功能一致。与其他铁透性酶类似，OmFET-GFP 定位于质膜上。OmFET 恢复了摄取缺陷型铁和锌菌株的生长。与空载体转化的细胞相比，表达 OmFET 的锌敏感酵母突变体特异性地积累镁。我们认为，OmFET 可能通过增加镁进入细胞来抵消锌的毒性。
