Two transporters mobilize magnesium from vacuolar stores to enable plant acclimation to magnesium deficiency
Two transporters mobilize magnesium from vacuolar stores to enable plant acclimation to magnesium deficiency
复制标题
两种转运蛋白从液泡储存中调动镁，使植物适应镁缺乏
DOI：
10.1093/plphys/kiac330
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发表时间：
2022
期刊：
影响因子：
7.4
通讯作者：
Luan, Sheng
中科院分区：
文献类型：
--
作者：
Tang, Ren-Jie;Yang, Yang;Yan, Yu-Wei;Mao, Dan-Dan;Yuan, Hong-Mei;Wang, Chao;Zhao, Fu-Geng;Luan, Sheng
镁（Mg）是植物细胞叶绿素合成和其他代谢过程中必需的金属。镁主要储存在各种细胞类型的液泡中，并重新动员以满足细胞质的需求。然而，负责调动液泡Mg 2+的转运蛋白仍然未知。在这里，我们确定了两个拟南芥（拟南芥）Mg 2+转运蛋白（Mg 2+转运蛋白1和2; MGT 1和MGT 2），促进Mg 2+动员从液泡，特别是当外部Mg供应是有限的。除了高度的序列相似性，MGT 1和MGT 2在拟南芥组织中表现出重叠的表达模式，这意味着功能冗余。事实上，在低镁条件下，与野生型相比，gt 1 mgt 2双突变体（而不是mgt 1和mgt 2单突变体）表现出夸大的生长缺陷，这与双突变体中镁饥饿基因标记的较高表达水平雅阁。然而，总体镁水平也较高，在mgt 1 mgt 2，这表明在镁离子再活化的缺陷，在响应镁缺乏症。MGT 1和MGT 2定位于液泡膜，并拯救了缺失液泡膜Mg ~（2+）外排转运蛋白的酿酒酵母mnr ~ 2 Δ（mannerresistance 2 Δ）突变株。此外，MGT 1和MGT 2的破坏抑制了钙调神经磷酸酶B样2和3（cbl 2 cbl 3），一个缺陷的液泡Mg 2+螯合突变体的高镁敏感性，表明液泡Mg 2+流入和流出过程是拮抗的生理背景下。我们进一步交叉mgt 1 mgt 2与mgt 6，这缺乏一个质膜MGT成员参与Mg 2+的吸收，并发现三重突变体是更敏感的低镁条件比eithermgt 1 mgt 2或mgt 6。因此，Mg 2+吸收（通过MGT 6）和液泡再动员（通过MGT 1和MGT 2）协同工作，以实现Mg 2+在植物体内的稳态，特别是在环境中的低Mg供应。
Magnesium (Mg) is an essential metal for chlorophyll biosynthesis and other metabolic processes in plant cells. Mg is largely stored in the vacuole of various cell types and remobilized to meet cytoplasmic demand. However, the transport proteins responsible for mobilizing vacuolar Mg2+remain unknown. Here, we identified two Arabidopsis (Arabidopsis thaliana) Mg2+transporters (MAGNESIUM TRANSPORTER 1 and 2; MGT1 and MGT2) that facilitate Mg2+mobilization from the vacuole, especially when external Mg supply is limited. In addition to a high degree of sequence similarity, MGT1 and MGT2 exhibited overlapping expression patterns in Arabidopsis tissues, implying functional redundancy. Indeed, themgt1 mgt2double mutant, but notmgt1andmgt2single mutants, showed exaggerated growth defects as compared to the wild type under low-Mg conditions, in accord with higher expression levels of Mg-starvation gene markers in the double mutant. However, overall Mg level was also higher inmgt1 mgt2, suggesting a defect in Mg2+remobilization in response to Mg deficiency. Consistently, MGT1 and MGT2 localized to the tonoplast and rescued the yeast (Saccharomyces cerevisiae)mnr2Δ(manganese resistance 2) mutant strain lacking the vacuolar Mg2+efflux transporter. In addition, disruption of MGT1 and MGT2 suppressed high-Mg sensitivity ofcalcineurin B-like 2and3 (cbl2 cbl3), a mutant defective in vacuolar Mg2+sequestration, suggesting that vacuolar Mg2+influx and efflux processes are antagonistic in a physiological context. We further crossedmgt1 mgt2withmgt6, which lacks a plasma membrane MGT member involved in Mg2+uptake, and found that the triple mutant was more sensitive to low-Mg conditions than eithermgt1 mgt2ormgt6. Hence, Mg2+uptake (via MGT6) and vacuolar remobilization (through MGT1 and MGT2) work synergistically to achieve Mg2+homeostasis in plants, especially under low-Mg supply in the environment.