The family of SMF metal ion transporters in yeast cells
The family of SMF metal ion transporters in yeast cells
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DOI：
10.1074/jbc.m004611200
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发表时间：
2000-10-27
影响因子：
4.8
通讯作者：
Nelson, N
中科院分区：
文献类型：
--
作者：
Cohen, A;Nelson, H;Nelson, N
金属离子对所有生物体都至关重要，金属离子转运蛋白在维持其体内平衡中起着至关重要的作用。酵母（Saccharomycescerevisiae）Smf转运蛋白及其在其他生物体中的同源物在金属离子的积累及其在不同组织和细胞器中的分布中具有核心作用。在这项工作中，我们在酵母中的每个单个SMF基因以及所有基因组合中产生了无效突变。每个无效突变在不同浓度下对金属离子螯合剂表现出敏感性。无效突变体Delta SMF 1 + Delta SMF 2和三重无效突变体Delta 3SMF的组合分别不能在pH 8和7.5缓冲的培养基上生长。添加5 μ M的铜或25 μ M的锰缓解了生长停滞在高pH值或在螯合剂的存在下，锰的运输进行了分析，在三重无效突变体，并在此突变体中表达每个Smf蛋白。虽然Smf1p和Smf2p的过表达导致摄取高于野生型细胞，但Smf3p的表达没有显著高于三重突变体Delta 3SMF的摄取。用抗Smf3p抗体进行的Western分析表明，这种转运蛋白不能到达质膜，可能在凝胶或凝胶后复合物中发挥作用。在铁转运蛋白FET3和FET4失活的突变体中分析了Smf1p和Smf2p表达引起的铁摄取。Smf1p的过表达引起了显着的铁吸收，是敏感的钠浓度在培养基中。我们的结论是Smf蛋白在铜和锰的体内平衡中起着重要作用，在某些情况下，Smf1p可能在铁转运到细胞中发挥作用。
Metal ions are vital for all organisms, and metal ion transporters play a crucial role in maintaining their homeostasis. The yeast (Saccharomyces cerevisiae) Smf transporters and their homologs in other organisms have a central role in the accumulation of metal ions and their distribution in different tissues and cellular organelles. In this work we generated null mutations in each individual SMF gene in yeast as well as in all combinations of the genes. Each null mutation exhibited sensitivity to metal ion chelators at different concentrations. The combination of null mutants Delta SMF1 + Delta SMF2 and the triple null mutant Delta 3SMF failed to grow on medium buffered at pH 8 and 7.5, respectively. Addition of 5 muM copper or 25 muM manganese alleviated the growth arrest at the high pH or in the presence of the chelating agent, The transport of manganese was analyzed in the triple null mutant and in this mutant expressing each Smf protein. Although overexpression of Smf1p and Smf2p resulted in uptake that was higher than wild type cells, the expression of Smf3p gave no significant uptake above that of the triple mutant Delta 3SMF. Western analysis with antibody against Smf3p indicated that this transporter does not reach the plasma membrane and may function at the Gels or post-Gels complexes. The iron uptake resulting from expression of Smf1p and Smf2p was analyzed in a mutant in which its iron transporters FET3 and FET4 were inactivated. Overexpression of Smf1p gave rise to a significant iron uptake that was sensitive to the sodium concentrations in the medium. We conclude that the Smf proteins play a major role in copper and manganese homeostasis and, under certain circumstances, Smf1p may function in iron transport into the cells.