Zhao H, Eide D
Department of Biochemistry and Molecular Biology, School of Medicine, University of Minnesota, Duluth 55812, USA.
Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2454-8. doi: 10.1073/pnas.93.6.2454.
The yeast Saccharomyces cerevisiae has two separate systems for zinc uptake. One system has high affinity for substrate and is induced in zinc-deficient cells. The second system has lower affinity and is not highly regulated by zinc status. The ZRT1 gene encodes the transporter for the high-affinity system, called Zrt1p. The predicted amino acid sequence of Zrt1p is similar to that of Irt1p, a probable Fe(II) transporter from Arabidopsis thaliana. Like Irt1p, Zrt1p contains eight potential transmembrane domains and a possible metal-binding domain. Consistent with the proposed role of ZRT1 in zinc uptake, overexpressing this gene increased high-affinity uptake activity, whereas disrupting it eliminated that activity and resulted in poor growth of the mutant in zinc-limited media. Furthermore, ZRT1 mRNA levels and uptake activity were closely correlated, as was zinc-limited induction of a ZRT1-lacZ fusion. These results suggest that ZRT1 is regulated at the transcriptional level by the intracellular concentration of zinc. ZRT1 is an additional member of a growing family of metal transport proteins.
酿酒酵母有两个独立的锌摄取系统。一个系统对底物具有高亲和力，并在缺锌细胞中被诱导。第二个系统亲和力较低，且不受锌状态的高度调节。ZRT1基因编码高亲和力系统的转运蛋白，称为Zrt1p。Zrt1p的预测氨基酸序列与Irt1p相似，Irt1p是拟南芥中一种可能的亚铁转运蛋白。与Irt1p一样，Zrt1p包含八个潜在的跨膜结构域和一个可能的金属结合结构域。与ZRT1在锌摄取中的假定作用一致，过表达该基因会增加高亲和力摄取活性，而破坏该基因则会消除该活性，并导致突变体在锌限制培养基中生长不良。此外，ZRT1 mRNA水平与摄取活性密切相关，ZRT1-lacZ融合蛋白的锌限制诱导也是如此。这些结果表明，ZRT1在转录水平上受细胞内锌浓度的调节。ZRT1是不断增加的金属转运蛋白家族中的另一个成员。
