A Single Amino Acid Change in Nramp6 from Sedum Alfredii Hance Affects Cadmium Accumulation

文献类型： 外文期刊

第一作者： Lu, Zhuchou

作者： Lu, Zhuchou;Chen, Shuangshuang;Han, Xiaojiao;Qiao, Guirong;Zhuo, Renying;Qiu, Wenmin;Lu, Zhuchou;Chen, Shuangshuang;Han, Xiaojiao;Qiao, Guirong;Zhuo, Renying;Qiu, Wenmin;Chen, Shuangshuang;Zhang, Jin;Jiang, Yugen

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关键词： Nramp6; Cadmium accumulation; site-directed mutagenesis; Sedum alfredii Hance

期刊名称：INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES （ 影响因子：5.923； 五年影响因子：6.132 ）

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年卷期： 2020 年 21 卷 9 期

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收录情况： SCI

摘要： SaNramp6 in Sedum alfredii encodes a membrane-localized metal transporter. We isolated the SaNramp6h allele from the hyperaccumulating ecotype (HE) of S. alfredii. When this allele was expressed in transgenic yeast and Arabidopsis thaliana, it enhanced their cadmium (Cd) sensitivity by increased Cd transport and accumulation. We isolated another allele, SaNramp6n, from a nonhyperaccumulating ecotype (NHE) of S. alfredii. Amino acid sequence comparisons revealed three amino acid differences between SaNramp6h and SaNramp6n. We investigated the Cd transport activity of the Nramp6 allele, and determined which residues are essential for the transport activity. We conducted structure-function analyses of SaNramp6 based on site-directed mutagenesis and functional assays of the mutants in yeast and Arabidopsis. The three residues that differed between SaNramp6h and SaNramp6n were mutated. Only the L157P mutation of SaNramp6h impaired Cd transport. The other mutations, S218N and T504A, did not affect the transport activity of SaNramp6h, indicating that these residues are not essential for metal selectivity. Transgenic plants overexpressing SaNramp6h(L157P) showed altered metal accumulation in shoots and roots. Our results suggest that the conserved site L157 is essential for the high metal transport activity of SaNramp6h. This information may be useful for limiting or increasing Cd transport by other plant natural resistance associated macrophage protein (NRAMP) proteins.

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