AtATM3 is involved in heavy metal resistance in Arabidopsis
AtATM3 is involved in heavy metal resistance in Arabidopsis
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DOI：
10.1104/pp.105.074146
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发表时间：
2006-03-01
期刊：
影响因子：
7.4
通讯作者：
Lee, Y
中科院分区：
文献类型：
--
作者：
Kim, DY;Bovet, L;Lee, Y
AtATM 3是拟南芥（Arabidopsis thaliana）的一种ATP结合盒转运蛋白，是一种线粒体蛋白，参与植物铁硫簇的生物合成和铁稳态。我们的基因表达分析表明，AtATM3在镉[Cd（II）]或铅（II）处理的植物根中上调，因此，我们调查了该基因是否参与重金属耐受性。我们发现，AtATM3过表达的植物增强了对镉的抗性，而atatm3突变体植物比野生型对照对镉更敏感。此外，atatm3突变体植物表达35S启动子驱动的AtATM3比野生型植物更耐镉。由于以往的报道往往表明，细胞内谷胱甘肽水平与重金属抗性呈正相关，我们测量了这些突变体植物的非蛋白硫醇（NPSH）。令人惊讶的是，我们发现atatm3在正常条件下比野生型含有更多的NPSH。AtATM3过表达植物在正常条件下没有不同，但含有较少的NPSH比野生型植物暴露于镉（II）。这些结果表明AtATM 3在调节细胞NPSH水平中的作用，我们的基因表达研究进一步支持了这一假设。谷胱甘肽生物合成的遗传或药理学抑制导致AtATM3的表达升高，而谷胱甘肽合成酶基因GSH 1的表达增加镉（II）胁迫下，在atatm3突变体。由于AtATM3在裂殖酵母（裂殖酵母），HMT1，最接近的同源物，是一个空泡膜定位的植物螯合素镉转运蛋白，它是诱人的推测，谷胱甘肽镉（II）复合物形成的线粒体中的AtATM3出口。总之，我们的数据表明，AtATM3有助于镉抗性，并表明它可能介导转运谷氨酰胺合成酶共轭镉（II）跨线粒体膜。
AtATM3, an ATP- binding cassette transporter of Arabidopsis ( Arabidopsis thaliana), is a mitochondrial protein involved in the biogenesis of iron-sulfur clusters and iron homeostasis in plants. Our gene expression analysis showed that AtATM3 is up-regulated in roots of plants treated with cadmium [Cd(II)] or lead ( II); hence, we investigated whether this gene is involved in heavy metal tolerance. We found that AtATM3-overexpressing plants were enhanced in resistance to Cd, whereas atatm3 mutant plants were more sensitive to Cd than their wild-type controls. Moreover, atatm3 mutant plants expressing 35S promoter-driven AtATM3 were more resistant to Cd than wild-type plants. Since previous reports often showed that the cytosolic glutathione level is positively correlated with heavy metal resistance, we measured nonprotein thiols (NPSH) in these mutant plants. Surprisingly, we found that atatm3 contained more NPSH than the wild type under normal conditions. AtATM3-overexpressing plants did not differ under normal conditions, but contained less NPSH than wild-type plants when exposed to Cd( II). These results suggest a role for AtATM3 in regulating cellular NPSH level, a hypothesis that was further supported by our gene expression study. Genetic or pharmacological inhibition of glutathione biosynthesis led to the elevated expression of AtATM3, whereas expression of the glutathione synthase gene GSH1 was increased under Cd( II) stress and in the atatm3 mutant. Because the closest homolog of AtATM3 in fission yeast (Schizosaccharomyces pombe), HMT1, is a vacuolar membrane-localized phytochelatin-Cd transporter, it is tempting to speculate that glutathione-Cd( II) complexes formed in the mitochondria are exported by AtATM3. In conclusion, our data show that AtATM3 contributes to Cd resistance and suggest that it may mediate transport of glutamine synthetase-conjugated Cd(II) across the mitochondrial membrane.