The homologous Arabidopsis MRS2/MGT/CorA-type Mg2+ channels, AtMRS2-10 and AtMRS2-1 exhibit different aluminum transport activity
The homologous Arabidopsis MRS2/MGT/CorA-type Mg2+ channels, AtMRS2-10 and AtMRS2-1 exhibit different aluminum transport activity
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DOI：
10.1016/j.bbamem.2018.08.016
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发表时间：
2018-11-01
影响因子：
3.4
通讯作者：
Sagami, Ikuko
中科院分区：
文献类型：
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作者：
Ishijima, Sumio;Manabe, Yuri;Sagami, Ikuko
镁（Mg2+）在许多生理过程中起着关键作用。AtMRS2/MGT家族由9个拟南芥基因（和2个伪基因）组成，属于CorA二价阳离子转运体超家族的真核亚群。AtMRS2-10和AtMRS2-1具有CorA超家族中保守的标志性GlyMetAsn序列；然而，它们与CorA的序列保守性较低。使用荧光染料mag-fura-2直接测量显示，重组的AtMRS2-10和AtMRS2-1介导Mg2+快速摄取到蛋白脂质体。铝抑制了AtMRS2-10对Mg2+的快速吸收。一项使用铝敏感染料morin的实验表明，铝通过AtMRS2-10被摄取到蛋白脂质体中。AtMRS2-10也表现出Ni2+转运活性，但几乎没有Co2+转运活性。铝不抑制AtMRS2-1对Mg2+的快速吸收。没有观察到通过AtMRS2-1进入蛋白脂质体的Al摄取。对大肠杆菌菌株TM2的功能互补实验表明，AtMRS2-1能够介导Mg2+的摄取。利用E. colt突变体细胞的异源表达也表明，表达AtMRS2-1的E. coil细胞比表达AtMRS2-10的E. cob细胞对铝的抗性更强。结果表明，AtMRS2-10将Al转运到大肠杆菌细胞中，并抑制了大肠杆菌的生长。AtMRS2-1定位于拟南芥叶绿体，表明AtMRS2-1暴露于铝的浓度远高于AtMRS2-10。在这种条件下，可能需要AtMRS2-1的Mg2+转运对Al的抑制不敏感，并且AtMRS2-1对Al是不渗透的。
Magnesium (Mg2+) plays a critical role in many physiological processes. The AtMRS2/MGT family, which consists of nine Arabidopsis genes (and two pseudo-genes) belongs to a eukaryotic subset of the CorA superfamily of divalent cation transporters. AtMRS2-10 and AtMRS2-1 possess the signature GlyMetAsn sequence conserved in the CorA superfamily; however, they have low sequence conservation with CorA. Direct measurement using the fluorescent dye mag-fura-2 revealed that reconstituted AtMRS2-10 and AtMRS2-1 mediated rapid Mg2+ uptake into proteoliposomes. The rapid Mg2+ uptake through AtMRS2-10 was inhibited by aluminum. An assay using the Al-sensitive dye morin indicated Al uptake into the proteoliposomes through AtMRS2-10. AtMRS2-10 also exhibited Ni2+ transport activity but almost no Co2+ transport activity. The rapid Mg2+ uptake through AtMRS2-1 was not inhibited by aluminum. Al uptake into the proteoliposomes through AtMRS2-1 was not observed. The functional complementation assay in Escherichia colt strain TM2 showed that AtMRS2-1 was capable of mediating Mg2+ uptake. Heterologous expression using the E. colt mutant cells also showed that the E. coil cells expressing AtMRS2-1 was more resistant to aluminum than the E. cob cells expressing AtMRS2-10. The results suggested that AtMRS2-10 transported Al into the E. colt cells, and then the transported Al inhibited the growth of E. colt. AtMRS2-1 has been localized to the Arabidopsis tonoplast, indicating that AtMRS2-1 is exposed to much higher concentration of aluminum than AtMRS2-10. Under the conditions, it may be required that the Mg2+ transport of AtMRS2-1 is insensitive to Al inhibition, and AtMRS2-1 is impermeable to Al.