Zinc transporter of Arabidopsis thaliana AtMTP1 is localized to vacuolar membranes and implicated in zinc homeostasis
Zinc transporter of Arabidopsis thaliana AtMTP1 is localized to vacuolar membranes and implicated in zinc homeostasis
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DOI：
10.1093/pcp/pci015
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发表时间：
2004-12-01
影响因子：
4.9
通讯作者：
Maeshima, M
中科院分区：
文献类型：
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作者：
Kobae, Y;Uemura, T;Maeshima, M
阳离子扩散促进蛋白（CDF）属于重金属外排转运蛋白家族，可能在体内平衡和对金属离子的耐受中发挥重要作用。我们研究了拟南芥AtMTP 1的亚细胞定位，CDF家族的成员，其生理作用的耐受锌使用MTP 1缺陷的突变体植物。AtMTP 1的免疫化学检测为一个43 kDa的蛋白质的液泡膜分馏蔗糖密度梯度离心。AtMTP 1在悬浮培养细胞中的表达水平不受培养基中Zn浓度的影响。当AtMTP 1与绿色荧光蛋白融合，在拟南芥悬浮培养细胞制备的原生质体中瞬时表达时，在液泡膜中清楚地观察到绿色荧光。AtMTP 1的T-DNA插入突变株系显示出对范围从200到500 μ M的高Zn浓度的增强的敏感性，但对Zn缺乏的条件不敏感。叶肉细胞的mtp 1 -1突变体植物生长在500 μ M的锌的存在下被降解，这表明锌在高浓度下会导致严重的损害叶和AtMTP 1起着至关重要的作用，在防止这种损害的植物。因此，我们建议，AtMTP 1是本地化的液泡膜，并参与螯合多余的锌在细胞质中进入液泡，以维持锌稳态。
Cation diffusion facilitator (CDF) proteins belong to a family of heavy metal efflux transporters that might play an essential role in homeostasis and tolerance to metal ions. We investigated the subcellular localization of Arabidopsis thaliana AtMTP1, a member of the CDF family, and its physiological role in the tolerance to Zn using MTP1-deficient mutant plants. AtMTP1 was immunochemically detected as a 43 kDa protein in the vacuolar membrane fractioned by sucrose density gradient centrifugation. The expression level of AtMTP1 in suspension-cultured cells was not affected by the Zn concentration in the medium. When AtMTP1 fused with green fluorescent protein was transiently expressed in protoplasts prepared from Arabidopsis suspension-cultured cells, green fluorescence was clearly observed in the vacuolar membrane. A T-DNA insertion mutant line for AtMTP1 displays enhanced sensitivity to high Zn concentrations ranging from 200 to 500 muM, but not to Zn-deficient conditions. Mesophyll cells of the mtp1-1 mutant plants grown in the presence of 500 muM Zn were degraded, suggesting that Zn at high concentrations causes serious damage to leaves and that AtMTP1 plays a crucial role in preventing this damage in plants. Thus we propose that AtMTP1 is localized in the vacuolar membrane and is involved in sequestration of excess Zn in the cytoplasm into vacuoles to maintain Zn homeostasis.