Shiraishi E, Inouhe M, Joho M, Tohoyama H
Department of Biology and Earth Science, Faculty of Science, Ehime University, Japan.
Curr Genet. 2000 Feb;37(2):79-86. doi: 10.1007/s002940050013.
Yeast cells carrying the CAD2 gene exhibit a resistance to cadmium. We cloned this gene and demonstrated that it was a mutated form derived from the gene of a putative copper-transporting ATPase (PCA1). By site-directed mutagenesis, it appeared that the mutation conferring cadmium resistance was a R970G-substitution in the C-terminal region of Pca1 protein. The intracellular cadmium level of cells carrying CAD2 was lower than that of cells carrying either PAC1 or delta cad2. Furthermore, cells with overexpression of CAD2 showed a much lower intracellular cadmium level than that of cells with a single-copy CAD2. From these results, we conclude that the Cad2 protein controls the intracellular cadmium level through an enhanced cadmium efflux system.
携带CAD2基因的酵母细胞对镉具有抗性。我们克隆了该基因，并证明它是一种推定的铜转运ATP酶（PCA1）基因的突变形式。通过定点诱变，似乎赋予镉抗性的突变是Pca1蛋白C末端区域的R970G替换。携带CAD2的细胞的细胞内镉水平低于携带PAC1或delta cad2的细胞。此外，CAD2过表达的细胞的细胞内镉水平比单拷贝CAD2的细胞低得多。从这些结果中，我们得出结论，Cad2蛋白通过增强的镉外排系统控制细胞内镉水平。
