Grotz N, Fox T, Connolly E, Park W, Guerinot M L, Eide D
Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
Proc Natl Acad Sci U S A. 1998 Jun 9;95(12):7220-4. doi: 10.1073/pnas.95.12.7220.
Millions of people worldwide suffer from nutritional imbalances of essential metals like zinc. These same metals, along with pollutants like cadmium and lead, contaminate soils at many sites around the world. In addition to posing a threat to human health, these metals can poison plants, livestock, and wildlife. Deciphering how metals are absorbed, transported, and incorporated as protein cofactors may help solve both of these problems. For example, edible plants could be engineered to serve as better dietary sources of metal nutrients, and other plant species could be tailored to remove metal ions from contaminated soils. We report here the cloning of the first zinc transporter genes from plants, the ZIP1, ZIP2, and ZIP3 genes of Arabidopsis thaliana. Expression in yeast of these closely related genes confers zinc uptake activities. In the plant, ZIP1 and ZIP3 are expressed in roots in response to zinc deficiency, suggesting that they transport zinc from the soil into the plant. Although expression of ZIP2 has not been detected, a fourth related Arabidopsis gene identified by genome sequencing, ZIP4, is induced in both shoots and roots of zinc-limited plants. Thus, ZIP4 may transport zinc intracellularly or between plant tissues. These ZIP proteins define a family of metal ion transporters that are found in plants, protozoa, fungi, invertebrates, and vertebrates, making it now possible to address questions of metal ion accumulation and homeostasis in diverse organisms.
全球数以百万计的人患有锌等必需金属的营养失衡问题。这些金属，连同镉和铅等污染物，污染了世界各地许多地方的土壤。这些金属除了对人类健康构成威胁外，还会毒害植物、牲畜和野生动物。弄清楚金属是如何被吸收、运输并作为蛋白质辅因子整合的，可能有助于解决这两个问题。例如，可以对可食用植物进行基因改造，使其成为更好的金属营养素膳食来源，还可以培育其他植物品种以从受污染土壤中去除金属离子。我们在此报告了从植物中克隆出的首个锌转运蛋白基因，即拟南芥的ZIP1、ZIP2和ZIP3基因。这些密切相关的基因在酵母中的表达赋予了锌摄取活性。在植物中，ZIP1和ZIP3在缺锌时在根中表达，这表明它们将锌从土壤转运到植物中。虽然尚未检测到ZIP2的表达，但通过基因组测序鉴定出的拟南芥的第四个相关基因ZIP4，在锌受限植物的地上部和根中均被诱导表达。因此，ZIP4可能在细胞内或植物组织之间转运锌。这些ZIP蛋白定义了一个金属离子转运蛋白家族，它们存在于植物、原生动物、真菌、无脊椎动物和脊椎动物中，这使得现在有可能解决不同生物体中金属离子积累和稳态的问题。
