Functional characterization of NRAMP3 and NRAMP4 from the metal hyperaccumulator Thlaspi caerulescens
Functional characterization of NRAMP3 and NRAMP4 from the metal hyperaccumulator Thlaspi caerulescens
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DOI：
10.1111/j.1469-8137.2008.02694.x
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发表时间：
2009-01-01
期刊：
影响因子：
9.4
通讯作者：
Thomine, Sebastien
中科院分区：
文献类型：
--
作者：
Oomen, Ronald J. F. J.;Wu, Jian;Thomine, Sebastien
金属超积累植物耐受和积累重金属的能力是金属稳态适应的结果。 NRAMP 金属转运蛋白被发现在一些超富集植物物种中高表达。在这里，我们鉴定了 TcNRAMP3 和 TcNRAMP4，它们是蓝藻中与 AtNRAMP3 和 AtNRAMP4 最接近的同源物，并通过表达分析、共焦成像和酵母和拟南芥中的异源表达对其进行了表征。TcNRAMP3 和 TcNRAMP4 的表达水平高于其 A.拟南芥同系物。当在酵母中表达时，TcNRAMP3 和 TcNRAMP4 转运与其各自拟南芥直系同源物相同的金属：铁 (Fe)、锰 (Mn) 和镉 (Cd)，但 NRAMP3 不转运锌 (Zn)； NRAMP4 的 Fe、Mn、Cd 和 Zn。它们还定位于拟南芥原生质体的液泡膜。拟南芥中 AtNRAMP3 和 AtNRAMP4 失活会导致强烈的 Cd 和 Zn 超敏反应，而 TcNRAMP3 或 TcNRAMP4 表达可以完全挽救这种情况。然而，nramp3nramp4突变体中TcNRAMP表达所赋予的金属耐受性并不超过野生型拟南芥。我们的数据表明，TcNRAMP3和TcNRAMP4及其拟南芥直系同源物之间的差异并不在于不同的蛋白质功能，而可能在于不同的表达水平或表达模式。New Phytographer (2009) 181: 637-650 doi：10.1111/j.1469-8137.2008.02694.x。
The ability of metal hyperaccumulating plants to tolerate and accumulate heavy metals results from adaptations of metal homeostasis. NRAMP metal transporters were found to be highly expressed in some hyperaccumulating plant species.Here, we identified TcNRAMP3 and TcNRAMP4, the closest homologues to AtNRAMP3 and AtNRAMP4 in Thlaspi caerulescens and characterized them by expression analysis, confocal imaging and heterologous expression in yeast and Arabidopsis thaliana.TcNRAMP3 and TcNRAMP4 are expressed at higher levels than their A. thaliana homologues. When expressed in yeast TcNRAMP3 and TcNRAMP4 transport the same metals as their respective A. thaliana orthologues: iron (Fe), manganese (Mn) and cadmium (Cd) but not zinc (Zn) for NRAMP3; Fe, Mn, Cd and Zn for NRAMP4. They also localize at the vacuolar membrane in A. thaliana protoplasts. Inactivation of AtNRAMP3 and AtNRAMP4 in A. thaliana results in strong Cd and Zn hypersensitivity, which is fully rescued by TcNRAMP3 or TcNRAMP4 expression. However, metal tolerance conferred by TcNRAMP expression in nramp3nramp4 mutant does not exceed that of wild-type A. thaliana.Our data indicate that the difference between TcNRAMP3 and TcNRAMP4 and their A. thaliana orthologues does not lie in a different protein function, but probably resides in a different expression level or expression pattern.New Phytologist (2009) 181: 637-650 doi: 10.1111/j.1469-8137.2008.02694.x.